acetone can take off spray paint and not the original.. as long as the cleacoat is still intact under the spray. put some on a towel and the rattle can will wipe right off. its about as non caustic as will actually do anything. you know, its nail polish remover and its about 5 dollars for a big can at most hardware stores.
I did that with my pinarello... unfortunately what was underneath was not pretty either. (someone had half stripped it down before rattle canning)