A hairdryer, and at least one good fingernail is all it ever took when I did it. If you are patient and peel slowly enough, all the adhesive will come off with the stripe. Get it started at one end, and then just move slowly along the car with the hairdryer, peeling slowly as you go, and it should all come off. One quick wipe afterward with some detail spray, and it'll look like the stripe never happened.