I got the 6" banner tint on the top of my windsheild. It has decided to discolor. I want to remove it and put some new tint on. What should I use to take the residue off once I get the film off?

This happens just after the warranty goes away!

1999 Contour SE Sony Xplod 50x4 cd player Sony Xplod 1600 watt Class D amp 2 10" Flame-Q Audiobahns 35% tint done by Madavi's Motor Sports