Heh.......I just did this yesterday.
Take a spary bottle and mix some dish washing detergent with water. Generously spray the window with this mixture, and then place some plastic over the tint. Something like a garbage bag will work. (I used the original plastic from which the tint peeled off of because my buddy just got done tinting another car). Park in the sun, windows completely shut, and when I say in the sun, make sure the window you are gonna peel is facing the sun, for about 45 minutes. It has to be a warm day too. A cold day will not do the trick. Then slowly start to peel the tint off the window. If it is not coming off easily, let it sit more. Otherwise, pull slowly and it should come off as one big piece.
Take some steel wool and gently wash the window, avoiding the defrosting lines. Good luck!