Turn the device upside down to reveal the rubber section of the back plate. Using a metal spudger, carefully wedge the blunt tip into the space between the aluminum back plate and the rubber, separating the two pieces.

This may take a few minutes to pry the rubber off completely. Once your are able to get a grip on the rubber it is easier to peel it off using your hands.

Depending on air temperature and how set the adhesive is, you may need to spend some time warming the back plate with a hot plate (on low) or hair dryer.

Don't worry about re-applying adhesive to the rubber; the remaining adhesive has plenty of strength to affix itself to the aluminum.