I've always used those dish cleaning things and ammonia to remove the goey stuff frome the deffroster lines. I don't know exactly what it's called. It's like a ball of plastic threads. It won't damage the defroster lines and it does a great job of getting the stuff off along with ammonia. Of course, use a razor and ammonia for removing the goo from the side windows. Tinting windows takes time and patience. If you're actually having problems taking the tint itself off, just spray it with ammonia as it's coming off. Be carefull and don't just rip it off fast, as it may take the defroster lines with it. Oh and yes, i'm a decent or i guess you could say good window tinter. Pretty much done it my whole life on and off. Just remember, ammonia removes it and dishwashing soap like joy puts it on. That's why they say to never use ammonia or windex to clean tinted windows. It may get between the glass and tint and make it peel off.