no no no.... Heat gun method leaves LOTS of glue behind typically.
Try this:
Get industrial grade ammonia cleaner at the hardware store. And a roll of saran wrap from the grocery store.
On a hot sunny day, spray the ammonia on the window film from the inside wetting the entire surface.
Working quickly, smooth saran wrap over the ammonia trapping it against the film.
Leave window with saran wrap and ammonia in direct sunlight for at least a hour.
Then SLOWLY peel the tint and saran wrap together.
Usually both layers of tint {tint layer and glue layer} will peel off almost completely in one piece this way, and no razor blade damage.