[P Glade]

A bit labor/time intensive but you might try laying the vinyl side down on a hard flat surface and see if a lot of it will "roll" or rub off with your hands. If it's still pliable and rubbery some may come off using this method. Then you could try a white or grey scotchbrite pad but pay attention if it's pulling the adhesive off and don't over-rub the "clean" areas (that should be a vinyl with a white sort of backing material on it).