How to Use the Windows 8.1 Start Button
You can open Task Manager from the Start Button.
A good example of how you can use the new Windows 8.1 Start Button is to open the Task Manager so that you can see and control which apps are currently running.
Right-click the Start Button and choose Task Manager from the pop-up menu to display the Task Manager window. Then you can select a running task from the list and click the End task button to shut down the selected app.