Display subcategories ONLY when selecting category from drop down menu

So I'm trying to figure out how to get the left sidebox to display only the subcategories when selecting a category from the top horizontal menu. Right now all categories and subcategories appear and you can drill down to the products.

Here is a link to my site:
http://tregreekboutique.com/zencart

For example, when selecting Sororities>Alpha Kappa Alpha, I only want Apparel, Headgear, Accessories, Jewelry, Mogul (Office), Auto, and Wood Products to appear.

Categories Dressing can do this kind of thing. You would want the chcategories option, and some settings in the define file (for active tree only, highest level 1, deepest level 9). The support thread has discussions of helping someone do this in the past few months.