Discount Tire has a special tool? Must've gotten those recently, thanks to my complaints to the company after a moron tech there tried taking my locks off with an impact, broke the key, and completely chewed the locks to the point where I had no choice, but to chisel them off (also gouging my wheels a little), and replace the studs. From then on, I take my wheels off, and bring them to the place to have tires mounted, watching them the whole time, so they don't screw my wheels up (ok, maybe I'm paranoid about it, but I've done it to peoples' wheels myself years ago, so it does happen). But anyway, pound on the smallest socket you can get to fit on the locks, and wrench them off. If that doesn't work, drill out the stud, and give it a whack with a hammer and chisel. It should break off easily, and you can replace the stud.
-Matt