Acetone, Carb clean come to mind. Goop off but it's a bit pricey. If you have a body shop nearby maybe they have some leftover paint(s) they can just blow over the "graphics". a couple of other option's: hit the local Home depot / lowes etc. They usually have mixed paint that was wrong for whatever reason, grab a roller as previously mentioned and go for it, or walmart's cheapest spray bomb paint