To clean an oven manually, sprinkle about a 1/4-inch layer of baking soda over the entire bottom of the oven. Use a clean spray bottle to wet the baking soda with water. Over the next few hours, spray the baking soda every so often to keep it moist. Then let the baking soda mixture sit overnight. In the morning, scrape and scoop the dried baking soda and grime out of the oven with a damp sponge. Rinse the residue off.
After you’ve done a major cleaning, finish the job by using a sponge to wipe down the entire surface with a mixture of half vinegar and half water. This will help prevent grease buildup. Be sure to give the entire interior a wipe once each week with a sponge soaked in pure vinegar.
If you have vents above your oven, check them about every six months for grease buildup. To clean, wipe the vents with a sponge soaked in pure vinegar. Use an old toothbrush dipped in vinegar to get at the grime that may have built up in small crevices or other hard-to-reach places. If the filter is metal and removable, soak it in a vinegar solution.