Hi,
when a RDP sessions hangs there are multiple ways to destroy it. The command line way:
Identify the RDP Session ID. Use quser
C:\>quser /Server:YourWindowsServer
USERNAME SESSIONNAME ID STATE IDLE TIME LOGON TIME
winuser rdp-tcp#6 2 Active 3 24.09.2014 22:26
Continue reading Windows: Howto terminate a RDP Session remotely by command line