Swipe down from the top of the screen to access the Quick Settings panel , then tap the gear icon (Settings). Alternatively, press the crown to open the app list and find the Settings app.
Select your Xiaomi Watch S1 from the list. How to Hard Reset XIAOMI Watch S1
Tap the green checkmark (✓) to confirm, or the red X to cancel. Swipe down from the top of the screen
Open the Mi Fitness app on your paired smartphone. How to Hard Reset XIAOMI Watch S1
Confirm the action. The app will send a command to the watch to perform a hard reset.
Tap on the Device tab (usually located at the bottom of the screen).