The solution can be found here:

http://www.basics.net/2013/02/25/win-server-2008-r2-how-to-enable-the-disk-cleanup-utility/

Use Option 2. because Option 1. is to install the Desktop Experience feature. However, this installs a lot of other utilities you likely don’t need on the Server.

With Option 1, you can immediately search and run cleanmgr.exe

The Disk Cleanup Utility does not clear the Windows System TEMP folder established in the environment variables.  Can anyone offer a solution for safely clearing the system TEMP folder? Please register and post your comment.  Thanks.