Use a hair dryer and then take off the residue with Goo Gone or Goof Off. If the stripes are fairly new they will come of easier. If they are old it may take a while but they will come off and the paint underneath should be fine. A razor blade in a holder will help but make sure to keep the area you are working on lubricated with a little Goo Gone or Goof Off so you do not scratch the paint. Be careful not to dig into the surface.
Steve
www.rallystripes.com