def leave_instance_group(self, instances,
                             instance_group,
                             **ignore):
        """ Delete the specific instance(s) from the group.
        @param instances: An id list contains the instance(s) who want to leave the instance group.
        @param instance_group: The instance group id.
        """
        action = const.ACTION_LEAVE_INSTANCE_GROUP
        valid_keys = ['instances', 'instance_group']
        body = filter_out_none(locals(), valid_keys)
        if not self.conn.req_checker.check_params(body,
                                                  required_params=['instances', 'instance_group'],
                                                  list_params=['instances']
                                                  ):
            return None

        return self.conn.send_request(action, body)