How to wipe my old Apple Watch before I trade it in?

PaulBar wrote:

purchased new apple watch. how do I clear data? and will this mess with new watch?

Apple provides a very helpful guide:

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

No it doesn’t affect your new Apple Watch ⌚️ follow the steps to unpair your old Apple Watch ⌚️

Unpair and erase your Apple Watch - Apple Support