it takes some time and attention. The residue and the actual tape have hardened and welded to the surface. You need to loosen or soften the residue with water, or wd40, or cleaners. The water or mositure has to penetrate the residue then it will scrape off with ease. Spray some wd40 on the stuff, let it sit for awhile, then re spray, let it sit then begin to scrape.