Peel the edge up with razor blade and remove tint. It will probably leave alot of the glue on the window. I use soapy water and spray the glass. keep it really wet and use new razor blades to remove the glue. Make sure to get in the weatherstrip channels. If you don't the glue will dry out again and the window may stick causing damage or make the glass hard to roll up.
I've been installing 3M tint for over 15 years and it's the way we do it.
If you use any solvent removers the glue will make a sticky mess.
John