Renaming Windows 2012R2 Server
Please refer to below video for the steps to rename a Windows 2012 R2 server. These steps will be working for any editions and versions of Windows Server from Windows 2012 till Windows 2012 R2 (and hopefully in future versions of Windows Servers too till Microsoft does major changes in GUI/navigation).
However please note that you need to be local administrator of the server your are renaming. Also you will need to restart the server to complete the change. So for production changes, you will need to plan for an planned restart if you need to rename a Windows Server.