diff --git a/biome.json b/biome.json
index 707c19672..df7fcded9 100644
--- a/biome.json
+++ b/biome.json
@@ -79,7 +79,6 @@
             "noConfusingVoidType": "off"
           },
           "performance": {
-            "noDelete": "off",
             "noAccumulatingSpread": "off"
           }
         }
diff --git a/src/components/test-slot/test-slot/__tests__/test-slot.spec.ts b/src/components/test-slot/test-slot/__tests__/test-slot.spec.ts
index f1d8b6030..3f7f48a2c 100644
--- a/src/components/test-slot/test-slot/__tests__/test-slot.spec.ts
+++ b/src/components/test-slot/test-slot/__tests__/test-slot.spec.ts
@@ -175,7 +175,7 @@ describe('TestSlotComponent', () => {
         expect(component.isIndicatorNeededForSlot()).toBe(false);
       });
       it('should return false if specialNeeds is missing', () => {
-        delete component.slot.booking.application;
+        component.slot.booking.application = undefined;
         expect(component.isAdditionalNeedsSlot()).toBe(false);
       });
       it('should return true if entitlementCheck is true (specialNeeds is blank, slotType is Standard)', () => {
@@ -186,7 +186,7 @@ describe('TestSlotComponent', () => {
       });
       it('should return false if entitlementCheck is missing (specialNeeds is blank, slotType is Standard)', () => {
         component.slot.booking.application.specialNeeds = '';
-        delete component.slot.booking.application.entitlementCheck;
+        component.slot.booking.application.entitlementCheck = undefined;
         component.slot.booking.application.specialNeedsCode = SpecialNeedsCode.NONE;
         expect(component.isIndicatorNeededForSlot()).toBe(false);
       });