If you want to hide running windows applications use WinRAP.WinRAP ( Windows Running Applications Protector ) is a utility which allows you to hide windows application, and hide programs which are running on your screen. It will instantly hide all or certain programs on your screen with a key press.
WinRAP is a tiny standalone tool which doesn’t have to be installed. It displays all running applications in the upper pane. You can hide each of the applications with a mouse click which moves the app’s name to the lower pane. The application’s interface will then disappear from the desktop. Of course, you can also unhide an application, if you want to access its interface.
Download WinRAP from here