code: def delete(self, namespace, key):
          
          if self.key_exists(namespace, key):
              obj = db.ConfigItem.find_one(
                  ConfigItem.namespace_prefix == namespace,
                  ConfigItem.key == key
              )
  
              del self.__data[namespace][key]
  
              db.session.delete(obj)
              db.session.commit()
          else:
              raise KeyError('{}/{}'.format(namespace, key))
docs: Remove a configuration item from the database
  
          Args:
              namespace (`str`): Namespace of the config item
              key (`str`): Key to delete
  
          Returns:
              `None`