How do I pair the Apple Watch with another iPhone?
I have an Apple Watch and a second iPhone. Now I need to unpair the Apple Watch from the first iPhone, and pair it with another iPhone. I want to keep all of my data though. How would I go about that? How would I continue?
Go to Watch< Apple Watch, then click Unpair Apple Watch. When you pair Apple Watch to the second device, all the data will be transferred.
You can also erase all content and settings on the watch and when it restarts it will have no apps or data and be ready to pair with another phone.
- https://support.apple.com/en-us/HT204568