The illustrated steps are helpful if you want to set up a new Apple Watch on your existing phone or pair your Apple Watch with a new phone
To do this, you will need to unpair it from your mobile device and back up its content and settings on your iPhone.
1. Open the Watch App on your iPhone to begin the process of unpairing your Apple Watch
2. Keep your iPhone and your Watch close together as you unpair them
3. Make sure your phone and your watch have the most recent software updates installed
4. Open the Apple Watch app on your iPhone to start unpairing it
5. Tap My Watch > All Watches at the top4. Open the Apple Watch app on your iPhone to start unpairing it
6. Tap the info (i) icon to the right of your watch that you want to unpair
7. Select Unpair Apple Watch at the bottom of the page
8. If the Watch has a cellular model, you need to keep or remove your monthly cellular data plan. Keep it if you want to pair your Apple Watch again to your phone and remove it if you are not using this one again. Tap to confirm
9. Enter your Apple ID password to turn off features like Activation Lock and Find My Watch
10.The phone will take a few minutes to complete the unpairing process while it will create a new backup of your watch. You can now use this backup to set up a new Apple Watch.
11.After it unpairs your Apple Watch, you can see it reboot to the language-choice screen. This is an indication that you’ve completed unpairing it from your iPhone
12. Once the watch is fully unpaired, you will see the message “Start Pairing”