Plastic film on windows?

previous owners put frosted plastic film on a plain window - they then decided to build a fake window ledge thus reducing the drop of the window from the inside, though outside you could still see the gl. We need to remove the plastic film but a false wall has been built in front of the gl so there isnt much room to get your hands in and peel it off - is there a product which can put on it to make to help its removal and not damage the gl ?