How to migrate from universal devices to iPhone only

In XCode, select the project (at the very top of the leftmost panel).

Then select it in TARGETS

Select General.

You will see in Deployment Info a Devices field.

Select iPhone here.

I know about this. But I can't deploy it to AppStore. I have an error

Do you update the App that was previously universal or is it a new app ?

Likely, you will have to resubmit an App

h ttps://stackoverflow.com/questions/44512139/is-it-possible-to-change-the-universal-app-to-iphone-only-once-it-is-uploaded-to

What error message do you get ?

You can't get there from here.

It's about taking something away from existing users that they've already obtained/paid for. You can migrate from iPhone to iPad, making a 'Universal' app (or go the other way), but you can't geld a Universal once it's been in the store.

I have an app which I (inadvertently) started as a universal app, but want it to be iPhone-only. I have uploaded universal builds to AppStoreConnect for Test Flight only, but the app is not yet released. Can I make the change now, or is it too late? -- JS