While the Apple Watch may be a new model, the iPhone model you pair it with may not be as new as it is. This is why it is important to know how to unpair your device when it starts acting up. A simply power cycle and force restart on your Apple Watch may not do anything to get rid of the problem. By unpairing your Watch and iPhone, you just might be able to restore your Apple Watch to its usual state.
Step 1: Open Apple Watch app from your iPhone device.
Step 2: Once the app has launched, tap on My Watch > Apple Watch. From there, you can tap on the Unpair Apple Watch option.
Step 3: The app will ask you to confirm the previous action. Tap again to confirm it. Once you have unpaired your Apple Watch to your device, you’ll see the message for Start Pairing.
Before you start to unpair your two devices, you have to keep them close to one another since the whole process is done through Bluetooth connection. If your iPhone is not with your or you had your Bluetooth disabled, you can simply go to Settings > General > Reset > Erase all Content and Settings on your Apple Watch. Keep in mind, however, that this won’t allow you to create an updated Watch backup.
Going with either option will completely wipe your wearable device clean and revert it to its default factory setting. It is only recommended that you unpair through the Apple Watch app if you need to perform a backup before removing your device from your paired devices. At the same time, you can easily restore your Watch from a save backup. This will let you pick up right where you left off.
You can also use this guide as a way to recover your Apple Watch passcode if ever you happen to forget what it is.