It's just a simple double back adhesive that they used. However, I used a hair blow dryer to "soften" the adhesive for easier removal. I set the blow dryer to low and aim at a letter for about 20secs. then I used an old credit card to pry off the letter. There will be some sticky residue but I used duct tape to remove it, using a side motion like "swiping" at first (don't go perpendicular as that won't do anything) then when the residue is minimal, perpendicular is fine. Once all the letters are removed I used a damp lint free cloth for the finishing wipe.