jQuery vertical mega-menu – how to get level-three to collapse?

This Widget is brilliant and stylish but i cannot get level-three menu items (sub-sub-menus)to collapse when only the level-one (main menu) item is clicked or hovvered. The behaviour I want is to show only level-two items subordinate to a single main menu item when that item is clicked or hovvered, then the same behaviour for sub- and sub-sub-menus.

Can it be done, please or is there a better plugin or widget for the purpose?