I wish I could help. I bought my daughter a car here in Florida and after her first year in NC with the car they said the tint was too dark but she had a local shop do the removal and it cost her I think about $150 bucks or so. She was not married at the time and had little choice and dad was over 1000 miles away so I couldn't get there.
Good luck, How about calling a local shop that installs it? I mean I am sure they do replacement jobs all the time so they must know a trick or two. When I put it on my home windows for hurricane protection, they soap up the windows pretty good then as it dries it sticks to the window...so I guess the reverse must be true. Trying to take it off without the soap will result in herniation.