Hello,
If you open the Start Menu and type slidetoshutdown and push Enter, you will see the slide to shutdown overlay appear.
You can also make a shortcut for this as well on your desktop; simply right-click any empty space on the desktop, select "New" then "Shortcut", and then type in slidetoshutdown and select "Next". Name it whatever you choose and then click "Finish". You can now slide to shut down your PC using that shortcut.
It may be that you need to push and hold the power button to shutdown instead of using the Start Menu.
I hope this information helps.