unpair Apple Watch series 6

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

Hello - Here are 4 articles to get your started.

Remove from Find My:

https://support.apple.com/guidehttps://support.apple.com/en-us/HT202704

Unpair and Erase Watch

https://support.apple.com/en-us/HT204568

Remove Device from your Apple ID:

https://support.apple.com/en-us/HT204568

Cancel prorated Apple Care (if purchased outright, or monthly)

https://support.apple.com/en-us/HT202704