Removing Keyboard Protector Imprint from Screen

I have an A1466 model (But I guess this can be relevant to any laptop in general),that has has a keyboard protector imprint or stain remaining on the display, the previous owner has obviously never taken off the KB cover when closing the display. I have tried rubbing it with screen cleaner, ISP and even gasoline but it is still there, Is there any reliable method to remove this that anyone has tried with some success? My guess is that it has left a permanent marking on the anti-glare coatings :( A reason why I never personally used them.