Galaxy Watch : How to reset ?
If your Galaxy Watch is frozen and unresponsive, press and hold the Home key (Power key) for more than 7 seconds to restart it.
If this does not solve the problem (i.e. the device still sometimes freezes after rebooting it as described above), perform a factory data reset.
To perform factory data reset Navigate to Apps screen → Tap Settings → General → Reset
Note: Before performing the factory data reset, remember to make backup copies of all important data stored in the Galaxy Watch.