Keep your iPhone and Apple Watch close together
Open the Watch app on your iPhone
Tap All Watches
Tap the info button next to your Apple Watch
Tap Unpair Apple Watch
Enter your Apple ID password if prompted
Wait for the unpairing process to finish
Set up your Apple Watch again
Turn on your Apple Watch
Hold it near your iPhone
Tap Continue on your iPhone when the pairing screen appears
Follow the on-screen instructions
Choose Restore from Backup if you want to restore data
Complete the setup process