Cleaning an oven is typically a tough job. By the time most people realize the oven needs to be cleaned, it's usually a mess. Cleaning an oven can be difficult because often it's covered with baked-on food and spattered grease. Oven cleaning can be a back-breaking job, especially if you don't or can't use commercial oven cleaners. You can easily clean your oven, however, by having the oven do most of the work.
Preheat your oven to 200 degrees, then shut it off.
Put 1 cup of non-sudsing household ammonia in an oven-safe bowl on the middle rack. Close the oven door and let the bowl of ammonia sit in your oven overnight.
Open the oven door the following morning. Be careful not to inhale the fumes and make sure your kitchen is well ventilated. Let the oven door stay open for 20 to 30 minutes. Remove the bowl and dispose of the ammonia.
Wipe down the entire inside of your oven using a wet sponge, clean wet rag or wet paper towels. Be sure to rinse out the sponge or rag and change paper towels often, otherwise you will end up spreading grease around rather than cleaning it off.