How do I clean an oven with vinegar?

I think you are thinking of a microwave or dishwasher. I don't think a cup of vinegar in the oven would do much.

I clean my oven with ammonia.

Heat the oven to 150 degrees Fahrenheit and turn it off. If you have a gas oven, turn off the gas and the pilot light. Place a pot of boiling water on the bottom rack. On the top rack, put a heat-safe bowl or baking dish containing 1 cup of ammonia. Shut the oven door and leave it overnight.

The next morning, open the oven and remove both the bowl of ammonia and the pot of water. Don’t dispose of the ammonia; you’ll want to use it later. Remove the racks and leave the oven door open to air out for 15 minutes. Add 1-2 teaspoons of liquid dish soap to the ammonia, along with a quart of warm water, and using a heavy-duty nylon scrubbing pad dipped in the ammonia mixture, begin to wipe away the softened grease and grime along the sides and bottom of the oven. It should be a fairly easy job at this point.

This is how I clean my oven:

https://www.hunker.com/12290358/how-to-clean-an-oven-with-vinegar-water

https://www.hometalk.com/search/posts?filter=clean%20oven

I've heard of cleaning a microwave using a glass cup full of water. Just put it in the microwave and heat the water for 2 or three minutes. Then let it sit for about 15 minutes to soften the grime and wipe it out. You could try making a paste with baking soda and water and spreading it on the oven interior. then covering with a damp cloth. Let it sit for a while and then spray it with white vinegar and wipe. Hard stuff can be scrapped carefully with a scraper or razor blade. I'm guessing you are trying to avoid using chemical oven cleaner. Some of them are not as bad as others, not as caustic or bad smelling. Good luck.

Here's a post that might help - https://chascrazycreations.com/natural-cleaning-with-vinegar/