How to upgrade iOS 16.1 to iOS 15.1

How to upgrade iOS 16.1 to iOS 15.1

This would be a downgrade from iOS 16.1 to iOS 15, which is not possible.

Updates are a one way street. Once you move up from one iOS to another higher system, you cannot go back.

That is not possible.

Apple moves forward, not back.

If you have any concerns:

Click ▶︎ Product Feedback. 

Not possible unless the update didn't update as expected (sometimes it doesn't) where you can go to Settings > General > iPhone Storage and delete the update. Most of the time it updates fine.