DIY
If you don't have a self-cleaning oven (which burns off residue at very high temperatures), try a paste of baking soda and water. Coat the oven surfaces with the paste (avoiding bare metal and heating elements), let stand overnight, and, while wearing gloves, use a plastic spatula to remove it.
Tips
To prevent future buildup, line the oven floor with aluminum foil, and wipe oven walls and ceiling after each spill. If you do have a self-cleaning oven, remove oven racks before running the cycle.
Aluminum foil on the bottom of the oven does not burn or catch on fire. Not sure what this person is talking about unless she is using cheap dollar store aluminum foil or even putting the elements on the foil. I have been using foil as long as I can remember and never have had a problem, it works great for me. Just throw away when something falls on it and replace. It really does save on the hard cleaning that needs to be done if not use. I highly recommend using the foil.
Aluminum foil applied to the bottom of the oven melts and ruins your oven. Very painful lesson to learn.
what's the easiest/best way to clean blown up baked potato from oven walls?
What is the best way to clean stainless steel appliances?
What is the best way to clean stainless steel appliances?
Making a paste of baking soda, citrasolve, and water works better than just backing soda and water. You need to rinse very well using baking soda however and it leaves residue.
I've heard that placing aluminum foil in the bottom of an oven can cause damage to the heating element and uneven heating while cooking. Is this true?