Finally a question I know something about!! haha
The easiest way to remove those suckers is to take the interior side panels off first, which means take the back seat out too, which is easier if the front seat is out of the car too, but not impossible with it in. Then you can reach your hand in and get the clips loose.
Like Brian said you probably need new ones, and I would recommend stevesnovasite.com ...its THE best Nova site.