I would suggest that you use a 'hot water ' sponge on the border to try and remove it. Give it a while and then imagine it is a beer bottle label. If that does not work I would suggest starting from re-decoration scratch. No simlpe answer - just hard work. Mind you ....worth it in the end.
I had the same problem with a Bart Simpson one... not one i put up i will add! It was a nightmare but between soapy water and water with fabric conditioner in it, it did come off. I would suggest soaking the border twice, before trying to scrap. Good Luck