It doesn't matter if you are having any issues or if you are ready to sell or give away your current watch, follow the Apple Watch factory reset procedure. We'll see how to do it with and without iPhone, even if you forgot your Apple Watch password. Before performing a factory reset with your Apple Watch, be sure to back it up if you want to restore your data to the same watch or a new one. If you back up your iPhone with iCloud or a Mac, an Apple Watch backup is automatically created. Keep in mind that iPhone backups on Mac must be encrypted for all data to be saved for Apple Watch. If you're having trouble with your Apple Watch, resetting and restarting it fixes all issues. Resetting an Apple Watch erases all user data and settings and returns the watch to its factory settings and software.
https://sites.google.com/view/resetapplewatchfactorysettings/home
https://sites.google.com/view/resetapplewatchfactorysettings/home