How do I clear the 'Awesome Bar'?

I use Firefox 4 now, and I do not like how the 'Awesome Bar' shows my 'Most Visited Sites' in a drop down menu, showing 'History and Bookmarks' is fine, but I don't like how the 'Most Visited' can't be deleted by clearing history, or hitting the 'Delete' on the keyboard, how would I fix this? I hate how it keeps my drop down bar all cluttered.