you can do this with the webmin-UI:
http://[YourMangoES-IP]:10000 or https://[YourMangoES-IP]:10000.
Enter mango/[YourPassword], in the left menu via /others/File Manager choose /opt/mango...
In the MangoES-box was also a manual that describes it and a note with the [YourPassword].
It looks like only for 3.5.x and lower:
Did you run cmd with admin status?
Since our last few win10 installations and a lot of trouble with win10 updates (delete the mango service via yajsw) we make it with the windows taskplaner and it works good and stable:
Sorry for the german version...