Buddy worked at a tint shop, this is what they did to take off when they needed to .If you have compressed air around, get a corner loose and hit it with a blower, 90 % of the time comes off in one sheet, then lots of a FOAM type window cleaner keeping it wet and scrape glue off with a blade. Make sure to keep it wet and sharp blade with a low angle to glass. Have removed for years like this and no problems.