In Windows Server 2008 R2 you could select whether you wanted to run Standard (GUI) or Core version of Windows Server. In Windows Server 2012 the GUI is a feature which you can add or remove.

To remove the GUI you use the following Powershell one-liner:

Remove-WindowsFeature Server-Gui-Shell, Server-Gui-Mgmt-Infra

You can also uninstall the GUI, which removes the binary files from the disk. To completely uninstall the GUI you use the following Powershell one-liner:

Uninstall-WindowsFeature Server-Gui-Shell, Server-Gui-Mgmt-Infra

If you realize you are in over your head you can add it back in using:

Add-WindowsFeature Server-Gui-Shell

… or:

Install-WindowsFeature Server-Gui-Mgmt-Infra,Server-Gui-Shell –Restart –Source c:\mountdir\windows\winsxs

You can also do all of this using Dism:

Dism /online /enable-feature /featurename:ServerCore-FullServer /featurename:Server-Gui-Shell /featurename:Server-Gui-Mgmt

Disclaimer.
The information in this article is provided “AS IS” with no warranties, and confers no rights. This article does not represent the thoughts, intentions, plans or strategies of my employer. It is solely my opinion.