I am going to have my car re-tinted because I want 5%. If they charge to remove old tint, I figure I mine as well do it myself to save some money. Anyways, what's the easiest way to remove the old tint?
Those ScotchBrite green nylon scrubby things, and some dishsoap. If you're doing the back glass, be VERY CAREFUL of the defroster if you want it to continue working.
There's this stuff- you can get it at Walmart or probably any auto parts store- called Tint-off. That removes the adhesive VERY well. Just peel the old tint off, and spray this stuff on, and use a razor blade to get the glue off. It comes off in big gooey chunks. Probably works just as well as Goo Gone, etc.
Go to WalMart or wherever and buy some Simple Green. Put it in a spray / mister bottle and spray down the entire window. Let it sit for awhile, and come back and peel the tint away. Whatever sticky film is left behind comes off the same way.
Learned this from a friend who works at a tint company, and it's so easy it's amazing.