protected function _remove($model, $where = array(), $msg = array('success' => '删除成功!', 'error' => '删除失败!'))
 {
     // 判断是否存在下级
     if (M($model)->where(['parent_uid' => ['in', M($model)->where($where)->getField('uid', true)]])->count()) {
         $this->error('此账号存在下级,无法管理删除!');
     }
     parent::_remove($model, $where, $msg);
 }