Let the oven cool, then carefully scrape the foil off with a razor blade. That should get the foil off!
Hot water scrubby sponge
Another way is to place a bowl of ammonia in a cold oven, let it set overnight. The fumes will do the work.
Then remove the ammonia, be sure there is good ventilation. Clean with a scrubbie or scrape off the stuck foil..
Debbie has it right! Good luck!