How do I shutdown the Syncthing?

I have search many times to restart or stop the syncthing with no luck or clear method to stop. Apparently, I tried to reboot the VM every time that needs to stop the syncthing.

I tried to pkill syncthing PID, not solved my issue

Any advise with detailed step?

Depends on thd platform and how you installed Syncthing.

On Linux you usually start and stop syncthings systemd (user) service.