How to remove Factory Windows Tint?
Remove any obstructions from the window, such as the rear brake light.
Spray the outside of the window with water and then cover it with plastic. Cut away excess plastic so that the tarp is roughly the shape of the window.
Lay a tarp across the rear deck and seats. Cover the front dashboard with plastic. Spray the inside of the window with pure ammonia. You may want to wear a face mask. Ammonia is very strong.
Cover the ammonia-soaked window with plastic and secure the plastic with tape.
Park the car in a sunny area. Leave the car for one hour.
Peel the tint off the window. Remove the plastic from the corner of the window. Leave as much the window covered as possible so the ammonia does not evaporate.
Spray the corner again with ammonia. Use a razor to pull away the corner of the tint. Be careful not to cut through any defroster lines or antennas. Once the corner rises, grab the loose piece with both hands and pull it away from the window. Pull slowly and with consistent pressure; the goal is to pull the film off in one piece. You will pull the plastic off as the tint pulls away from the window. If necessary, spray ammonia as you pull. If the tint film breaks, spray ammonia and use the razor to restart it.
Scrub off the adhesive residue stuck to the window once the film comes off. Spray the window glass again with ammonia. Use a fine steel wool pad to scrub off the adhesive.