diff --git a/api/controllers/service_api/app/annotation.py b/api/controllers/service_api/app/annotation.py
index ef254ca357..c22190cbc9 100644
--- a/api/controllers/service_api/app/annotation.py
+++ b/api/controllers/service_api/app/annotation.py
@@ -185,4 +185,4 @@ class AnnotationUpdateDeleteApi(Resource):
     def delete(self, app_model: App, annotation_id: str):
         """Delete an annotation."""
         AppAnnotationService.delete_app_annotation(app_model.id, annotation_id)
-        return {"result": "success"}, 204
+        return "", 204
diff --git a/api/controllers/service_api/app/conversation.py b/api/controllers/service_api/app/conversation.py
index 8e29c9ff0f..edbf011656 100644
--- a/api/controllers/service_api/app/conversation.py
+++ b/api/controllers/service_api/app/conversation.py
@@ -14,7 +14,6 @@ from controllers.service_api.wraps import FetchUserArg, WhereisUserArg, validate
 from core.app.entities.app_invoke_entities import InvokeFrom
 from extensions.ext_database import db
 from fields.conversation_fields import (
-    ConversationDelete,
     ConversationInfiniteScrollPagination,
     SimpleConversation,
 )
@@ -163,7 +162,7 @@ class ConversationDetailApi(Resource):
             ConversationService.delete(app_model, conversation_id, end_user)
         except services.errors.conversation.ConversationNotExistsError:
             raise NotFound("Conversation Not Exists.")
-        return ConversationDelete(result="success").model_dump(mode="json"), 204
+        return "", 204
 
 
 @service_api_ns.route("/conversations/<uuid:c_id>/name")