Home depot, 1" plastic scraper, in the paint dept, they're a white poly plastic, very forgiving and not knife edge sharp, by Hyde Mfg (maker of all good drywall tools). Equivalent of much more expensive body shop tools for about $1.
As above recommendation, heat gun or hair dryer, and PATIENCE. You can try to soften the adhesive with a little rubbing alcohol first, but the heat is what will release the bond (no fires pls).
