Honestly, this is your best option. It shouldn't cost too much for one window, but you know that once you glue it it will start bubbling or something...

I'd wait a while to see how bad it gets, then get it redone when it looks like shit.


About the original post, I've heard you're supposed to use a steam cleaner to remove it, that or do what someone else said: wrap it in a trashbag with water and let it soak. Its the best way to get it off easily. scrubbing all that stuff off is gonna suck, lol.