Tap the red minus sign next to your Apple ID. However, you can change it on your iPhone and then use the new one to sign in to Apple Watch. Click on the “Edit” button to remove the old number.
However, many users have trouble finding the option that enables them to change their Apple ID. Tap on “Sign Out” on the top right of the screen. you can do advanced configuration of your iCloud email account. Found insidechange or reenter your password and change the description of your account.