How do I delete update 14.3 from my Apple 6 iphone?

First of all iPhone 6 does not have iOS 14.3

Secondly, if you have iPhone 6S and iOS 14.3, you can't roll back.

What about for an XR? Typically you can go to iPhone storage then IOS then gives you the option to delete the update to create more space in your phone but now that’s not a option anymore?