All you need is regular baking soda and water to clean your oven naturally.
How to Use Them
Sprinkle the bottom of your oven with baking soda until it's completely covered--about 1/4 inch will do. Spray the baking soda with water until it's damp. Leave the solution for a few hours, then spray it with water to dampen it again. Leave the solution overnight. In the morning, wipe out the oven with a sponge.
When spraying the baking soda with water, don't flood it. Too much water is not be good for the cleaning process. The only downside to this process is a white residue that's left from the baking soda; you may have to wipe out the oven more than once.