Bleach
This mixture should be used only if you need to clean really tough stains. Wear protective gloves and a face mask while performing this. Take 1½ tsp. of bleach, ½ tsp. of dishwashing liquid, ½ tsp. of lemon juice, and 1 qt. of warm water in a bucket and mix well. Apply this solution using a sponge for the insides of the oven, and let it stand for an hour. Clean away the mixture using a damp cloth, and then another to get rid of any dampness.