code: function() {
          // We need to make sure any pending images are canceled so the world items don't get messed up
          this.viewer._cancelPendingImages();
          var item;
          var i;
          for (i = 0; i < this._items.length; i++) {
              item = this._items[i];
              item.removeHandler('bounds-change', this._delegatedFigureSizes);
              item.removeHandler('clip-change', this._delegatedFigureSizes);
              item.destroy();
          }
  
          var removedItems = this._items;
          this._items = [];
          this._figureSizes();
          this._needsDraw = true;
  
          for (i = 0; i < removedItems.length; i++) {
              item = removedItems[i];
              this._raiseRemoveItem(item);
          }
      }
docs: Remove all items.
  @fires OpenSeadragon.World.event:remove-item
  @fires OpenSeadragon.World.event:metrics-change