I didn’t get a 1099 but TurboTax keeps asking me to fill one in. I did not have any IRA distributions in 2018. Why can’t I skip this and file?

If you had a distribution in 2017, then the form carried over.  Enter 1099-R in the Find window, hit enter, then click the Jump To.  When you come to the little summary showing the empty 1099-R, delete it.