I just had to have mine removed for the same reason. I paid a mobile tinter to remove it ($80!!..damn good deal!)
He used a heat gun on the outside of the window, then slowly peeled it back. When he had it off, he sprayed a strong ammonia based solvent onto the glass and then put the tint back on over it! this sealed the fumes in and made it dissolve the GLUE that is left behind. He then removed the tint again (Easily pulled it off) then wiped the glue residue off with some cotton lint. Then he used a soap / ammonia mix and libberally applied it then use a rubber squeegee to remove remaining glue. Then more soap/ammonia and wiped it clean (This was the rear window with demister) The side windows he used the same technique (Some tint he just pulled off without heat..depends if it started to tear or not) he only used a metal razor blade on side windows..not the squuegee. When using the blade he scraped about 6 inches in one move..then flicked the glue off (Onto the removed tint) repeated a few times till clean..
Took him about 1.5 hours to remove it. I had 3 different tint films on my windows (Thankyou dodgy arse solartint in campbletown!!) even though I paid $325 for the best tint I could buy. and had it put on all at once!
Personally it would have taken me 4-5 hours..$80 was cheap!