How can I reset an Apple Watch that I bought from someone
How can I make an Apple Watch that I bought from reset and connect to my phone without knowing other persons Apple ID
iPhone 12 Pro, iOS 15
Question marked as
You can't remove their ID without their Apple ID and password. The seller needs to do the steps in the article below. The article also covers what you need to do before buying a watch.
Watch - What to do before you sell, give away, or trade in your watch, or buy one from someone else. *