help removing glue residue from LCD screen???

I had a screen protector for a cell phone on my camera screen, and it had chipped up in one corner and was driving me crazy, so I decided to pull it off and use a new screen protector for my new phone. When I pulled it off, it revealed a terrible residue left on the screen. I want to know the best way to remove it without damaging my screen. I hesitantly used some rubbing alcohol to no avail. You will see a few lines going across the screen, that is where i scratched it with my nails.

Does anyone have any ideas???

Thanks for your help.