code: function( element ) {
          var i;
  
          element = $.getElement( element );
          i = getOverlayIndex( this.currentOverlays, element );
  
          if ( i >= 0 ) {
              this.currentOverlays[ i ].destroy();
              this.currentOverlays.splice( i, 1 );
              THIS[ this.hash ].forceRedraw = true;
              /**
               * Raised when an overlay is removed from the viewer
               * (see {@link OpenSeadragon.Viewer#removeOverlay}).
               *
               * @event remove-overlay
               * @memberof OpenSeadragon.Viewer
               * @type {object}
               * @property {OpenSeadragon.Viewer} eventSource - A reference to the
               * Viewer which raised the event.
               * @property {Element} element - The overlay element.
               * @property {?Object} userData - Arbitrary subscriber-defined object.
               */
              this.raiseEvent( 'remove-overlay', {
                  element: element
              });
          }
          return this;
      }
docs: Removes an overlay identified by the reference element or element id
  and schedules an update.
  @method
  @param {Element|String} element - A reference to the element or an
  element id which represent the ovelay content to be removed.
  @return {OpenSeadragon.Viewer} Chainable.
  @fires OpenSeadragon.Viewer.event:remove-overlay