the trick is there's three layers, the black top layer, a fibrous layer, and the actual adhesive. I think it's best to try to peel back as much of the the fibrous layer as you can while you peel back the black layer, using your nails. Then put a drop of alcohol (I used 90%) on the sticky part, and try to scratch off some of the remaining fibrous layer with your nail. If you don't do this it's hard to wipe up the adhesive. After the fibrous layer has at least been broken, you can use a towel (regular, not paper) soaked in alcohol to work on the adhesive. it takes a lot of rubbing, but I found it helps to support the back side since the metal bits are pretty flexible. Once it's pretty clean, you'll find some of the alcohol/adhesive mixture has soaked through to the other side of the metal, so you'll need to clean that with a clean section of towel soaked in alcohol again