To prevent users from shutting down the server via Server Operating systems, you can cancel the SHUT DOWN key as follows.

We go to Start > Run > gpedit.msc .

Then, we log in to: Windows Settings > Security Settings > Local Policies > User Rights Assignmet > Shut Down The system .

As in the Image below;
You add which user or group of users you want to shut down the server with the Add User or Group bot.
To prevent any user or user group from shutting down the server, you remove it with the Remove button.

Then you say OK .