Transfer cellular plan to new Apple Watch
I have a Series 6 AW and will transfer the cellular plan to a new Ultra 2 AW. I am keeping the 6, just need to transfer the cellular plan
You can delete the eSim on your Apple Watch 6 in Settings/Cellular/ in the Watch App on your iPhone.
You may have to contact your carrier before that, in case you need a code for the eSIM setup on your Apple Watch Ultra 2.