Deregistering phone number from I message
I no longer have access to my work phone and number but it is still attached to my personal phone - how do I disconnect it from my personal phone?
iPhone 7, iOS 15
Question marked as
Add or remove your phone number in Messages or FaceTime - Apple Support would seem to have the answer
If the phone number that you want to remove belongs to an iPhone that you can't access, change your Apple ID password. This removes all phone numbers from your iPad, iPod touch, and Mac. Calls or messages for the removed numbers won't appear on those devices anymore.
If you have questions, contact Apple Support.