How I disabled the "Log Off" Button

Follow the given steps to disable Turn off Computer" button on the start menu:

To use this feature, you will need to be logged into your computer with administrative rights.

Click Start button and type regedit in Run option then press Enter for next.

Here locate the location to:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer

Here in right side panel, right click to create a new DWORD value with the name NoClose.