code: function (map) {
          var del = this._delegate || this;
          del.onLayerWillUnmount && del.onLayerWillUnmount(); // -- callback
  
  
          map.getPanes().overlayPane.removeChild(this._canvas);
  
          map.off(this.getEvents(), this);
  
          this._canvas = null;
  
      }
docs: -------------------------------------------------------------