My MIL hasd a habit of lining things to keep them "clean". She also had aluminum foil permanently stuck to the bottom of her oven. And paper towels dried up inside her refrigerator. I wish I had a good suggestion for you.

I have a hunch that, if you run the cleaning cycle, the foil will probably flake off and end up as dust on the bottom which can be wiped off.

I'd be willing to bet the foil is stuck to a previous spill. Try a razor blade, held almost horizontally so as not to gouge the surface. Slow and careful.

The bottom of ours is easily removable, so I take it out to do anything like this. (easier on my back). Yes, its self cleaning, but manual says to scrape/clean any large spills beforehand and I always overfill lasagna pan.

This recently came up on the kitchens board.

Here is a link that might be useful: Link from Kitchens

Boy, this answers my questions about using aluminum foil on the bottom of my new self cleaning oven. My coils are underneath. I was looking around and just read somewhere that a woman just ordered another bottom from the manufacturer for her oven. Her husband thought he was helping to keep the bottom clean by putting foil there.She paid about $45 for the new bottom. She did it herself (or her husband did). There are two screws they removed and lifted out the old bottom and replaced it with the new one. Done deal! Check out the manufacturers of the unit and just replace that piece. It sounds like it was worth it. She was digusted every time she used the oven with the aluminum foil stuck to it.......This may also include any silicone liners too. You will have to check with your manufacturers......Roxy