delete tags when their resource is deleted

moto/events/models.py

@@ -143,6 +143,8 @@ class EventsBackend(BaseBackend):
 
     def delete_rule(self, name):
         self.rules_order.pop(self.rules_order.index(name))
+        arn = self.rules.get(name).arn
+        self.tagger.delete_all_tags_for_resource(arn)
         return self.rules.pop(name) is not None
 
     def describe_rule(self, name):

moto/utilities/tagging_service.py

@@ -12,6 +12,9 @@ class TaggingService:
                 result.append({self.keyName: k, self.valueName: v})
         return {self.tagName: result}
 
+    def delete_all_tags_for_resource(self, arn):
+        del self.tags[arn]
+
     def tag_resource(self, arn, tags):
         if arn not in self.tags:
             self.tags[arn] = {}