How do I unlink an iPhone from an Apple ID?

How to Remove Apple ID from iPhone

Use your iPhone, iPad, or iPod

1. On your iPhone, iPad or iPod touch, tap Settings > Your Name.
2. Scroll down and you will see your list of Apple ID devices. You will see every device that is connected to your Apple account.
3. Tap any device name that you want to remove.
4. And tap Remove from Account. Then tap again to confirm.

How to Remove Apple ID From iPhone without Password