How do I disconnect someone’s Apple ID from an apple watch

The person that you bought this watch from needs to follow all the steps in this link;

Prepare the watch so the buyer can use it.

If they can't or won't then get your money back or recycle the watch and put it down to experience.

Follow this guide from Apple:

https://support.apple.com/en-us/HT208855

Bellarose9 wrote:

How do I disconnect someone’s Apple ID from a Apple watch

You get that person information to remove the activation lock.