use a dremel to cut them. Or some sort of cutting wheel.
If you're in a real shit show of a spot you can jam your least favorite screwdriver under them and warp them out enough you can get tin snips on them.
If you can't afford an authentic dremel (which are awesome as hell to have around), you can get one from Harbor Freight. Rotary Tool Kit, 80 Pc. Probably won't last the longest but it'll save you such a damn headache.