The safest way is to sand the paint off. Step your sand paper down( 180-280-400-500-600) until a smooth surface is achived. Plastic is fairly simple, but carbon firber would be more chalanging. When you sand through to the carbon fiber sub-strate you can't sand over that spot anymore. IF YOU SAND THROUGH THE RESIN AND EXPOSE THE FIBER ITS DONE. Some companies sell chemicals that remove paint but usually end up swelling the plastic type part. One other point: if all you want is color change, just sand the part. Get rid of the gloss(all the shiney) the factory the origanaly painted the part did a better job than any of us could do in our garage.