Ghacks posted a quick tutorial about configuring Windows to shut down automatically

Windows does not provide users with easy options to schedule automatic shut downs of the system. While it is possible to use the Windows Task Scheduler for that, using the built-in tool is not a pleasant experience. Some users may prefer a simpler solution that they can configure in a heartbeat whenever it is needed.

Wise Auto Shutdown is a free program for all recent versions of the Windows operating system that offers exactly that functionality. When you start the program after installation you are presented with a single-screen configuration menu that enables you to configure automatic power state changes.

  Configure Windows to shut down automatically