That is a real crap shoot.. some come off in a nice big piece with a heat gun and patience. SOME DONT.
You may have to pick at it little by little, or you MAY try an 3M eraser wheel on an electric drill.
(If it doesnt peel off, anything else you do is time consuming.)
If you use the eraser wheel, be certain to be gentle until you get a "feel" for how it works, be certain not to damage your paint!
be careful. ... Wang.