What command should you run?

Accordingly to all the resources that I found, removing server-gui-mgmt-infra, won’t remove server-gui-shell, and it will result in a 2012R2 Minimal Server Interface Installation.

As stated in MSDN (https://msdn.microsoft.com/pt-br/library/hh831786(v=ws.11).aspx)
For example, to completely remove Windows Explorer, Internet Explorer, and dependent components, run the following Windows PowerShell command:

Uninstall-WindowsFeature Server-Gui-Shell -Remove

To me, this is incomplete, but, if I find this on the test, I’ll mark only the first one, since everywhere is stating this.

The given answer is correct.

If you run Uninstall-WindowsFeature server-gui-mgmt-infra from a “server with a GUI” installation, all GUI interfaces will be removed, resulting in a “Server Core” installation. You will be left with only command prompt and PowerShell.

From Microsoft: “If you convert to a Server Core installation, Windows features, server roles, and GUI management tools that require a Server with a GUI installation will be uninstalled automatically.”
https://technet.microsoft.com/en-us/library/hh831786(v=ws.11).aspx

Running uninstall-windowsfeature server-gui-shell will give you a “Minimal Server Interface” installation. This will remove most of the GUI interfaces on the server; only Server Manager, a subset of Control Panel items, and MMC will remain (command prompt and PowerShell will also be available).

You don’t need to run uninstall-windowsfeature server-gui-shell before running uninstall-windowsfeature server-gui-mgmt-infra.