My phone says there’s an update but when I go check there’s no update

Follow all instructions here, including restoring from the latest publicly available iOS version.

How to uninstall iOS beta software - Apple Support

Well, again you are asking us to guess a whole lot. We have no idea what steps you performed, what you saw after each step, what worked, what failed, what error messages you received, what type of computer is involved with which software version numbers, etc.

Might you be using beta software and failed to tell us?