Some simple household items and a little bit of time are all you need.
The inside of your oven is probably a lot dirtier than you'd like to admit. Fortunately, it's easy to clean. The following method works well if your oven doesn't have a self-clean cycle, or if you simply want to spot-clean it without using harsh cleaning products. And since you're probably self-isolating at home right now, now is as good a time as any for some spring cleaning.
Remove the racks from your oven and wash them in warm, soapy water. Some oven racks are dishwasher-safe, but check your oven manual first to make sure they won't be damaged in the dishwasher. Dry the racks and set them aside.
Wipe away any loose food particles in your oven.
Make a paste using three parts baking soda and one part water. You can "ballpark" this measurement and adjust as needed to achieve a pasty consistency.
Spread the baking soda paste around the inside of your oven. If there are really tough, burnt-on spots, put a little extra paste on them. Avoid putting the paste on heating elements inside the oven.
Close your oven, and let the paste sit overnight.
Moisten your sponge or cleaning cloth with warm water and wipe away the baking soda paste. You may need to rinse the sponge as you go to clean off bits of paste. For any stubborn messes, use a scraper or a spatula.
Fill a spray bottle with one part vinegar and one part water. Spray down the oven and wipe away leftover baking soda paste with your sponge.
Return the racks to your oven; you can start cooking now.
Further reading: It's almost grilling season -- here's how to clean your grill.