Hi,
Erm, yes, just delete the category. I can't see the point of having a category with no links to it.
Even if you added sites to the category, no-one would see them as there wouldn't be a link to it from its parent category. Or ... am I missing the point?
I think my original suggestion may be what you're looking for, you just might need to see it in action to understand how it would operate. Visit
www.qango.com and try submitting to any of the top-level categories, then try others another level down, and so on. This should give you an idea of how it works in practice. Does this help at all?
Cheers,
Shaun