My dealer used vinyl. Therefore, I have used thin sharp blades that used in the drywall (Sheetrock) cutter. I couldn't use blade for the one on the rear bumper. I simply used my nails to get that off. If you can do it early enough (before the vinyl get really sticky), you can take it off with nail. But if your dealer uses paint, then I am not sure what's the procedure.
Used blade:
Simply nails: