For 2021, I reported a small sum as "other self-employed income..." I did not have that kind of income in 2022 but TurboTax won't allow me to enter 0 or remove that line

If TurboTax is generating Schedule C Profit or Loss From Business but you no longer have a business, you'll need to remove the business that transferred over from last year. 

• Click on the following for instructions: How do I delete a prior-year Schedule C business that transferred over?

You may need to do some other things to "close" your business. Click here for more information.