diff --git a/messages/tier4_external_api_msgs/CMakeLists.txt b/messages/tier4_external_api_msgs/CMakeLists.txt
index cba69db8f0485..923e10dc89f63 100644
--- a/messages/tier4_external_api_msgs/CMakeLists.txt
+++ b/messages/tier4_external_api_msgs/CMakeLists.txt
@@ -15,52 +15,23 @@ find_package(ament_cmake_auto REQUIRED)
 ament_auto_find_build_dependencies()
 
 rosidl_generate_interfaces(${PROJECT_NAME}
-  msg/ClassifiedDiagnostics.msg
   msg/ControlCommand.msg
   msg/ControlCommandStamped.msg
-  msg/DoorStatus.msg
   msg/Emergency.msg
   msg/EngageStatus.msg
-  msg/FailSafeState.msg
-  msg/FailSafeStateStamped.msg
   msg/GearShift.msg
   msg/GearShiftStamped.msg
   msg/Heartbeat.msg
   msg/MapHash.msg
-  msg/MetadataPackages.msg
-  msg/Observer.msg
-  msg/Operator.msg
   msg/ResponseStatus.msg
-  msg/Route.msg
-  msg/RouteSection.msg
-  msg/Service.msg
-  msg/TextFile.msg
-  msg/Steering.msg
   msg/TurnSignal.msg
   msg/TurnSignalStamped.msg
-  msg/VehicleCommand.msg
-  msg/VehicleCommandStamped.msg
-  msg/VehicleStatus.msg
-  msg/VehicleStatusStamped.msg
-  srv/ClearRoute.srv
   srv/Engage.srv
-  srv/GetMetadataPackages.srv
-  srv/GetTextFile.srv
-  srv/GetVersion.srv
   srv/InitializePose.srv
   srv/InitializePoseAuto.srv
-  srv/PauseDriving.srv
-  srv/SetDoor.srv
-  srv/SetObserver.srv
-  srv/SetOperator.srv
   srv/SetEmergency.srv
-  srv/SetPose.srv
-  srv/SetRoute.srv
-  srv/SetService.srv
-  srv/SetVelocityLimit.srv
   DEPENDENCIES
     builtin_interfaces
-    diagnostic_msgs
     geometry_msgs
 )
 
diff --git a/messages/tier4_external_api_msgs/msg/ClassifiedDiagnostics.msg b/messages/tier4_external_api_msgs/msg/ClassifiedDiagnostics.msg
deleted file mode 100644
index 943546654a1b3..0000000000000
--- a/messages/tier4_external_api_msgs/msg/ClassifiedDiagnostics.msg
+++ /dev/null
@@ -1,2 +0,0 @@
-builtin_interfaces/Time stamp
-diagnostic_msgs/DiagnosticStatus[] diagnostics_notice
diff --git a/messages/tier4_external_api_msgs/msg/DoorStatus.msg b/messages/tier4_external_api_msgs/msg/DoorStatus.msg
deleted file mode 100644
index 10428618bd6b0..0000000000000
--- a/messages/tier4_external_api_msgs/msg/DoorStatus.msg
+++ /dev/null
@@ -1,11 +0,0 @@
-# constants
-int8 NOT_SUPPORTED = -1
-int8 UNKNOWN = 0
-int8 OPENED = 1
-int8 CLOSED = 2
-int8 OPENING = 3
-int8 CLOSING = 4
-
-# fields
-builtin_interfaces/Time stamp
-int8 status
diff --git a/messages/tier4_external_api_msgs/msg/FailSafeState.msg b/messages/tier4_external_api_msgs/msg/FailSafeState.msg
deleted file mode 100644
index f5abbbeb7e82b..0000000000000
--- a/messages/tier4_external_api_msgs/msg/FailSafeState.msg
+++ /dev/null
@@ -1,9 +0,0 @@
-# constants
-uint8 NORMAL = 1
-uint8 OVERRIDE_REQUESTING = 2
-uint8 MRM_OPERATING = 3
-uint8 MRM_SUCCEEDED = 4
-uint8 MRM_FAILED = 5
-
-# fields
-uint8 state
diff --git a/messages/tier4_external_api_msgs/msg/FailSafeStateStamped.msg b/messages/tier4_external_api_msgs/msg/FailSafeStateStamped.msg
deleted file mode 100644
index a9ddc6247c42e..0000000000000
--- a/messages/tier4_external_api_msgs/msg/FailSafeStateStamped.msg
+++ /dev/null
@@ -1,2 +0,0 @@
-builtin_interfaces/Time stamp
-tier4_external_api_msgs/FailSafeState state
diff --git a/messages/tier4_external_api_msgs/msg/MetadataPackages.msg b/messages/tier4_external_api_msgs/msg/MetadataPackages.msg
deleted file mode 100644
index 638ae995b7e3c..0000000000000
--- a/messages/tier4_external_api_msgs/msg/MetadataPackages.msg
+++ /dev/null
@@ -1,2 +0,0 @@
-string format
-string json
diff --git a/messages/tier4_external_api_msgs/msg/Observer.msg b/messages/tier4_external_api_msgs/msg/Observer.msg
deleted file mode 100644
index 3f472c8b929d1..0000000000000
--- a/messages/tier4_external_api_msgs/msg/Observer.msg
+++ /dev/null
@@ -1,7 +0,0 @@
-# constants
-# uint8 NONE=1 (reserved)
-uint8 LOCAL=2
-uint8 REMOTE=3
-
-# fields
-uint8 mode
diff --git a/messages/tier4_external_api_msgs/msg/Operator.msg b/messages/tier4_external_api_msgs/msg/Operator.msg
deleted file mode 100644
index 18d508c615e96..0000000000000
--- a/messages/tier4_external_api_msgs/msg/Operator.msg
+++ /dev/null
@@ -1,7 +0,0 @@
-# constants
-uint8 DRIVER=1
-uint8 AUTONOMOUS=2
-uint8 OBSERVER=3
-
-# fields
-uint8 mode
diff --git a/messages/tier4_external_api_msgs/msg/Route.msg b/messages/tier4_external_api_msgs/msg/Route.msg
deleted file mode 100644
index dc159f43bcf8f..0000000000000
--- a/messages/tier4_external_api_msgs/msg/Route.msg
+++ /dev/null
@@ -1,2 +0,0 @@
-geometry_msgs/PoseStamped goal_pose
-tier4_external_api_msgs/RouteSection[] route_sections
diff --git a/messages/tier4_external_api_msgs/msg/RouteSection.msg b/messages/tier4_external_api_msgs/msg/RouteSection.msg
deleted file mode 100644
index 9c056b7049735..0000000000000
--- a/messages/tier4_external_api_msgs/msg/RouteSection.msg
+++ /dev/null
@@ -1,3 +0,0 @@
-int64 preferred_lane_id
-int64[] lane_ids
-int64[] continued_lane_ids
diff --git a/messages/tier4_external_api_msgs/msg/Service.msg b/messages/tier4_external_api_msgs/msg/Service.msg
deleted file mode 100644
index 2630a53714e50..0000000000000
--- a/messages/tier4_external_api_msgs/msg/Service.msg
+++ /dev/null
@@ -1,6 +0,0 @@
-# constants
-uint8 NOT_IN_SERVICE=1
-uint8 IN_SERVICE=2
-
-# fields
-uint8 mode
diff --git a/messages/tier4_external_api_msgs/msg/Steering.msg b/messages/tier4_external_api_msgs/msg/Steering.msg
deleted file mode 100644
index c4705704f3464..0000000000000
--- a/messages/tier4_external_api_msgs/msg/Steering.msg
+++ /dev/null
@@ -1 +0,0 @@
-float32 data
diff --git a/messages/tier4_external_api_msgs/msg/TextFile.msg b/messages/tier4_external_api_msgs/msg/TextFile.msg
deleted file mode 100644
index 7866644a83726..0000000000000
--- a/messages/tier4_external_api_msgs/msg/TextFile.msg
+++ /dev/null
@@ -1 +0,0 @@
-string text
diff --git a/messages/tier4_external_api_msgs/msg/VehicleCommand.msg b/messages/tier4_external_api_msgs/msg/VehicleCommand.msg
deleted file mode 100644
index a0a3652f1291a..0000000000000
--- a/messages/tier4_external_api_msgs/msg/VehicleCommand.msg
+++ /dev/null
@@ -1,2 +0,0 @@
-float64 velocity
-float64 acceleration
diff --git a/messages/tier4_external_api_msgs/msg/VehicleCommandStamped.msg b/messages/tier4_external_api_msgs/msg/VehicleCommandStamped.msg
deleted file mode 100644
index 73a354bd469a1..0000000000000
--- a/messages/tier4_external_api_msgs/msg/VehicleCommandStamped.msg
+++ /dev/null
@@ -1,2 +0,0 @@
-builtin_interfaces/Time stamp
-tier4_external_api_msgs/VehicleCommand command
diff --git a/messages/tier4_external_api_msgs/msg/VehicleStatus.msg b/messages/tier4_external_api_msgs/msg/VehicleStatus.msg
deleted file mode 100644
index 4fa6bee40252e..0000000000000
--- a/messages/tier4_external_api_msgs/msg/VehicleStatus.msg
+++ /dev/null
@@ -1,4 +0,0 @@
-geometry_msgs/Twist twist
-tier4_external_api_msgs/Steering steering
-tier4_external_api_msgs/TurnSignal turn_signal
-tier4_external_api_msgs/GearShift gear_shift
diff --git a/messages/tier4_external_api_msgs/msg/VehicleStatusStamped.msg b/messages/tier4_external_api_msgs/msg/VehicleStatusStamped.msg
deleted file mode 100644
index 13cfb2a601b8a..0000000000000
--- a/messages/tier4_external_api_msgs/msg/VehicleStatusStamped.msg
+++ /dev/null
@@ -1,2 +0,0 @@
-builtin_interfaces/Time stamp
-tier4_external_api_msgs/VehicleStatus status
diff --git a/messages/tier4_external_api_msgs/package.xml b/messages/tier4_external_api_msgs/package.xml
index 4bd3353cafc0e..b36e272ee627b 100644
--- a/messages/tier4_external_api_msgs/package.xml
+++ b/messages/tier4_external_api_msgs/package.xml
@@ -16,7 +16,6 @@
   <exec_depend>builtin_interfaces</exec_depend>
   <exec_depend>rosidl_default_runtime</exec_depend>
 
-  <depend>diagnostic_msgs</depend>
   <depend>geometry_msgs</depend>
 
   <test_depend>ament_lint_auto</test_depend>
diff --git a/messages/tier4_external_api_msgs/srv/ClearRoute.srv b/messages/tier4_external_api_msgs/srv/ClearRoute.srv
deleted file mode 100644
index 0563cb5b15e64..0000000000000
--- a/messages/tier4_external_api_msgs/srv/ClearRoute.srv
+++ /dev/null
@@ -1,2 +0,0 @@
----
-tier4_external_api_msgs/ResponseStatus status
diff --git a/messages/tier4_external_api_msgs/srv/GetMetadataPackages.srv b/messages/tier4_external_api_msgs/srv/GetMetadataPackages.srv
deleted file mode 100644
index 7b62e4348b10a..0000000000000
--- a/messages/tier4_external_api_msgs/srv/GetMetadataPackages.srv
+++ /dev/null
@@ -1,3 +0,0 @@
----
-tier4_external_api_msgs/ResponseStatus status
-tier4_external_api_msgs/MetadataPackages metadata
diff --git a/messages/tier4_external_api_msgs/srv/GetTextFile.srv b/messages/tier4_external_api_msgs/srv/GetTextFile.srv
deleted file mode 100644
index a341bc5df3fc9..0000000000000
--- a/messages/tier4_external_api_msgs/srv/GetTextFile.srv
+++ /dev/null
@@ -1,3 +0,0 @@
----
-tier4_external_api_msgs/ResponseStatus status
-tier4_external_api_msgs/TextFile file
diff --git a/messages/tier4_external_api_msgs/srv/GetVersion.srv b/messages/tier4_external_api_msgs/srv/GetVersion.srv
deleted file mode 100644
index fa9f5fd1cb581..0000000000000
--- a/messages/tier4_external_api_msgs/srv/GetVersion.srv
+++ /dev/null
@@ -1,3 +0,0 @@
----
-tier4_external_api_msgs/ResponseStatus status
-string version
diff --git a/messages/tier4_external_api_msgs/srv/PauseDriving.srv b/messages/tier4_external_api_msgs/srv/PauseDriving.srv
deleted file mode 100644
index 3430334d020b7..0000000000000
--- a/messages/tier4_external_api_msgs/srv/PauseDriving.srv
+++ /dev/null
@@ -1,3 +0,0 @@
-bool pause
----
-tier4_external_api_msgs/ResponseStatus status
diff --git a/messages/tier4_external_api_msgs/srv/SetDoor.srv b/messages/tier4_external_api_msgs/srv/SetDoor.srv
deleted file mode 100644
index 6a89566f41f5d..0000000000000
--- a/messages/tier4_external_api_msgs/srv/SetDoor.srv
+++ /dev/null
@@ -1,3 +0,0 @@
-bool open
----
-tier4_external_api_msgs/ResponseStatus status
diff --git a/messages/tier4_external_api_msgs/srv/SetObserver.srv b/messages/tier4_external_api_msgs/srv/SetObserver.srv
deleted file mode 100644
index 80b092f925e37..0000000000000
--- a/messages/tier4_external_api_msgs/srv/SetObserver.srv
+++ /dev/null
@@ -1,3 +0,0 @@
-tier4_external_api_msgs/Observer mode
----
-tier4_external_api_msgs/ResponseStatus status
diff --git a/messages/tier4_external_api_msgs/srv/SetOperator.srv b/messages/tier4_external_api_msgs/srv/SetOperator.srv
deleted file mode 100644
index 5156c3029f9fe..0000000000000
--- a/messages/tier4_external_api_msgs/srv/SetOperator.srv
+++ /dev/null
@@ -1,3 +0,0 @@
-tier4_external_api_msgs/Operator mode
----
-tier4_external_api_msgs/ResponseStatus status
diff --git a/messages/tier4_external_api_msgs/srv/SetPose.srv b/messages/tier4_external_api_msgs/srv/SetPose.srv
deleted file mode 100644
index 898ae8c7544a9..0000000000000
--- a/messages/tier4_external_api_msgs/srv/SetPose.srv
+++ /dev/null
@@ -1,3 +0,0 @@
-geometry_msgs/PoseStamped pose
----
-tier4_external_api_msgs/ResponseStatus status
diff --git a/messages/tier4_external_api_msgs/srv/SetRoute.srv b/messages/tier4_external_api_msgs/srv/SetRoute.srv
deleted file mode 100644
index 522541931a094..0000000000000
--- a/messages/tier4_external_api_msgs/srv/SetRoute.srv
+++ /dev/null
@@ -1,3 +0,0 @@
-tier4_external_api_msgs/Route route
----
-tier4_external_api_msgs/ResponseStatus status
diff --git a/messages/tier4_external_api_msgs/srv/SetService.srv b/messages/tier4_external_api_msgs/srv/SetService.srv
deleted file mode 100644
index 7ddea0396d8c4..0000000000000
--- a/messages/tier4_external_api_msgs/srv/SetService.srv
+++ /dev/null
@@ -1,3 +0,0 @@
-tier4_external_api_msgs/Service mode
----
-tier4_external_api_msgs/ResponseStatus status
diff --git a/messages/tier4_external_api_msgs/srv/SetVelocityLimit.srv b/messages/tier4_external_api_msgs/srv/SetVelocityLimit.srv
deleted file mode 100644
index 9c9b22bc727f3..0000000000000
--- a/messages/tier4_external_api_msgs/srv/SetVelocityLimit.srv
+++ /dev/null
@@ -1,3 +0,0 @@
-float32 velocity
----
-tier4_external_api_msgs/ResponseStatus status