code: function() {
          this.map.events.un({
              "removelayer": this.updateAttribution,
              "addlayer": this.updateAttribution,
              "changelayer": this.updateAttribution,
              "changebaselayer": this.updateAttribution,
              scope: this
          });
          
          OpenLayers.Control.prototype.destroy.apply(this, arguments);
      }
docs: Constructor: OpenLayers.Control.Attribution
  
  Parameters:
  options - {Object} Options for control.
   
  Method: destroy
  Destroy control.