first Apply some water to a small section of the adhesive. If the adhesive used was organic mastic, the water will begin to soften it, allowing you to scrape it off.
Apply an adhesive-removing paste to the wall.
Let the paste soften the wall adhesive.
Scrape down the walls with a putty knife, removing the softened adhesive.
Put some on a clean cloth and rub on the offending area. Give it 5 - 10 minutes and then rub over again. The same amount of time should be enough to start to see it lift off.
I've also heard that Nail Varnish Remover would also do the trick, but don't quote me on that.
You could try using a glass scraper on it. It shouldn't damage the panel as long as you keep it really flat. Would help if you could soften it a bit first though.