code: public <E> void delete(Class<E> entityClass, DatastoreKey parentKey, long id) {
      try {
        EntityMetadata entityMetadata = EntityIntrospector.introspect(entityClass);
        Key nativeKey = Key.newBuilder(parentKey.nativeKey(), entityMetadata.getKind(), id).build();
        nativeWriter.delete(nativeKey);
      } catch (DatastoreException exp) {
        throw DatastoreUtils.wrap(exp);
      }
    }
docs: Deletes the entity with the given ID and parent key.
  
  @param entityClass
  the entity class.
  @param parentKey
  the parent key
  @param id
  the ID of the entity.
  @throws EntityManagerException
  if any error occurs while inserting.