Apple watch series 3

What do you mean replace the owner? If you purchased a used Apple Watch and it is Activation Locked to the previous owner, ONLY they can unlock the watch. Apple will NOT unlock the watch. We cannot help you unlock the watch.

So, if you bought a used Apple Watch, get them to remove the watch from their account. If you don't actually know or can't reach them, the watch is totally useless to you and you should try to get your money back. If you can't get your money back, recycle the watch responsibly as you can never use it.

Read this --> The All Too Common SAD Reality of Buying … - Apple Community

If you are the current owner and want to transfer the watch to someone else, see the 'Before you sell, give away, or trade in your Apple Watch' section in:

What to do before you sell, give away, or trade in your Apple Watch, or buy one from someone else - Apple Support

Activation Lock is designed to prevent anyone else from using an Apple Watch if it's ever lost or stolen.

About Activation Lock on your Apple Watch - Apple Support

Activation Lock is an anti-theft feature that cannot be bypassed. Only the previous owner can remove the lock by using their Apple ID & password. Apple will not help you find the previous owner. If the previous owner cannot or will not remove the lock, then the watch is useless to you or anyone else. Try to get a refund (through eBay) or dispose of the watch properly. In the future, see the 'Before you buy a watch from a third-party' section in:

What to do before you sell, give away, or trade in your Apple Watch, or buy one from someone else - Apple Support

You're welcome. I wrote the user tip I linked in my response. Please make sure that if you ever buy a used Apple product, if you can't see it in person and see it has been prepared properly for a new user DO NOT BUY IT.

Apple has a Refurbished Store, where you can buy Apple Certified Refurbished devices at discount, which come with a full one year warranty. ONLY buy from trusted sources.

Take care.