I just did this last month. I am sure brownbear's method works, but if you want a no mess removal, just use heat.
Truck was parked in the garage. I put a small electric heater in the truck a couple of hours before I started to let it get pretty warm in there. Then used a blow drier at the point of attack. A razorblade is helpful in getting a corner started. Then just grab and slowly pull while waving the blow drier just ahead of where your pulling.
I found that if I went slower with the pulling and used plenty of heat, then there was virtually no adhesive residue left on the glass, but if I got hurried pulling on the stuff, it would leave behind some sticky stuff that required a little attention with solvent.
Truck looks so much better without the purple tint. I love the look of the clean glass. The factory glass has nice suttle tint/color to it.