code: func (client *cniClient) del(runtimeConfig libcni.RuntimeConf,
  	cfg *Config,
  	pluginConfigFunc func(*Config) (string, *libcni.NetworkConfig, error)) error {
  
  	deviceName, networkConfig, err := pluginConfigFunc(cfg)
  	if err != nil {
  		return err
  	}
  	runtimeConfig.IfName = deviceName
  
  	return client.libcni.DelNetwork(networkConfig, &runtimeConfig)
  }
docs: // del invokes the DEL command of the given plugin