How to Edit Menu on MAC OS X

To edit Main menu on mac locate the file and edit the

#/System/Library/Frameworks/Carbon.framework/Versions/A/Frameworks/HIToolbox.framework/Versions/A/Resources/English.lproj/StandardMenus.nib/objects.xib

If You want to disable the Shutdown from the menu, execute below commands from terminal.

sudo defaults write /Library/Preferences/com.apple.loginwindow ShutDownDisabled -bool true

sudo defaults write /Library/Preferences/com.apple.loginwindow ShutDownDisabledWhileLoggedIn -bool true