Razor blades are the easy way to remove it from all but the rear window. Don't use a razor on the defroster lines!
Use a quality scraper handle, brand new blade, and change the blade often. Obviously, if you nick the blade, it's going to scratch your glass, so don't do that!
After 10 years, my tint finally failed on my old Acura, and that's exactly what I did to get it off. It did take a couple hours, and lots of vacuuming later, but it worked just fine.
1978 13BT-40, 70 series mechanicals
1966 FJ45 lwb stock
2003 100 stock
1974V8J40, 1992FJ80, 1985FJ60, 1971FJ55, 1978FJ40, 1974FJ40, 1997 LX450 all long gone.