How to Add Power button and the Shut Down, Restart, Sleep, and Hibernate

1. Press the Windows key + R to bring up the Run box. Type gpedit.msc and press Enter to open the Local Group Policy Editor.
2. In left-side pane, navigate to Computer Configuration -> User Configuration  -> Administrative Template -> Start Menu and Taskbar.
3. In the right pane select the “Remove and prevent users from access to Shut Down, Restart, Sleep, and Hibernate commands” double-click on it. Select Disable and click Apply and OK.