If you don't have a steamer, "black bag" it. Spray ammonia or ammonia based cleaner on the tint inside of the window and immediately place a cut to size black trash bag over top that. Park the car in the sun for 30-90 minutes. Use a single edge blade and carefully peel back just a corner of the film until you can get a grip on it. Peel off the tint and trash bag simultaneously. I tint so this is where my information is coming from FYI.