Best bet is to just buy either heat tape or a heat tape style UTH like a Ultratherm or Flukers. Then you only need a roll of foil tape and can mount and unmounts it millions of times. Otherwise if its like a Zoo Med one, then pretty much what PitOnTheProwl said.
Peel them really slowly and try not to bend it. I've removed a few Zoo Med ones and they are a pain, just have to go slow.