I had to peel the tint off of my side windows a few months ago due to a cop saying it was too dark.I just peeled the old tint off and the glue pretty much stayed on the window.Then I used some isoprophyl alcohol (sp) to clean the remaining glue residue off.I wouldnt go using a razor blade on your back window just in case you damage the defrost lines.Other than that its pretty easy, just alot of scrubbing.