I often get asked, how to remove window film. There are a couple of different adhesive types and depending what kind it is, the method changes a little.
First, car film, safety film, frosted film and some solar films are made with PS (Pressure Sensitive) adhesive. This means the film will adhere mechanically straight away. This glue is easiest to remove.
On cars, have the car outside in the sun, if possible to warm up the glass. Step 1: With a small razor blade or knife, peel away from one corner. Slowly! If you're lucky, the whole sheet will come off. Unfortunately, this is not the case very often. If it's hard to peel, stop and spray the film with glass cleaner containing ammonia. Use an old black plastic rubbish bag and place it over the film for a few minutes. This slows down the evaporation and softens the glue. Repeat step 1.
On rear windows with demister bars, ensure you don't use a scraper, otherwise you will damage the lines. You can use "Goldilocks" or similar non-scratch scouring pads.
Once all the film is off, you are left with a lot of glue. There are some adhesive removers on the market that work well, but care must be taken not to get any on upholstery or other surfaces. You can use glass cleaner and new razor blades and go over it a few times and it will come off.
If you get the car tinted again, ask them them to give you a price for removing it. If you do a bad job, leaving adhesive residue, they will probably charge you to clean it up anyway.