How do I remove vinyl from windows

I've just taken over an office with some really old and ugly coverings on the windows which I presume to be vinyl.

I've tried peeling them off to varied success. On a couple of windows, the vinyl came off in large strips but left behind piles of dry adhesive - I managed to get the adhesive off with a razor blade type tool. But on the majority of windows, the vinyl just won't budge without hours of hard graft.

I suspect there will be substances available to remove the adhesive. But on several windows I'm not even getting down that far.

What do I do?

Somebody told me they're not designed to come off so I'm kinda stuck.

Advice wil be greatly appreciated.

Thanks.

question is what are they there for?

may be because the glass is plate and should be laminated

I assume they're there just to stop the sun coming in so harshly. Only some of the windows have it so it's clearly not essential.

I need a fresher look so I'm happy for the sun to come in.


W.

Hairdryer. with patience it should all come off in one go. Any adhesive left over can be removed with solvent cleaner.