code: func DeleteKeyFromEtcd(key string, etcdCli *clientv3.Client, retryCnt int, timeout time.Duration) error {
  	var err error
  	ctx := context.Background()
  	for i := 0; i < retryCnt; i++ {
  		childCtx, cancel := context.WithTimeout(ctx, timeout)
  		_, err = etcdCli.Delete(childCtx, key)
  		cancel()
  		if err == nil {
  			return nil
  		}
  		logutil.Logger(ddlLogCtx).Warn("[ddl] etcd-cli delete key failed", zap.String("key", key), zap.Error(err), zap.Int("retryCnt", i))
  	}
  	return errors.Trace(err)
  }
docs: // DeleteKeyFromEtcd deletes key value from etcd.