To reset your Apple Watch, follow these steps:

1. Press and hold the side button until you see the Power Off slider.
2. Drag the slider to the right to turn off your Apple Watch.
3. Once your Apple Watch is off, press and hold the side button again until the Apple logo appears. This will take a few seconds.
4. Your Apple Watch will now restart and should be reset to its default settings.

Note: Resetting your Apple Watch will erase all data and settings, so make sure to back up your data before resetting if you want to keep it.