Having worked at a movie theater, I can tell you that the answer is “by a human”
If you can make a machine that cleans a popcorn popper well enough to pass a health inspection, you’ll be a very rich person. Especially a small vending-machine-sized popper-and-dispenser all-in-one jobby.
You’re talking to someone that’s talking about walking on water. It’s obviously Jesus’s Lemmy account