I had to use pliers to pull off big pieces, a sharp knife to scrape off small pieces followed by a utility knife or razor with a handle to get rid of the contact cement underneath. Sandpaper did nothing and the solvents I tried were no help at all. It doesn't matter if you scrape the metal as long as you replace it with new neoprene or carpet. It honestly was a bitch to do. It took several hours of several days to get everything off. There's probably an easier way, I just used what I had.