There should be a way to do it through the local security policy. I do see a policy object that should control this behavior, and on my server it's set this way by default, where it seems to do what you're interested in. Well, try it, see what happens, then come back and tell me because I'd like to know.
Click Start -> Run (Or press WinKey + R)
Type in "gpedit.msc" and hit Ok.
Go to Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> User Rights Assignment.
Double click the policy named "Shut down the system."
Remove "Users" from the list and click Ok. (It should now only say Administrators and Backup Operators.)
Now go to Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options.
Double click the policy named "Shutdown: Allow system to be shut down without having to log on."
Set it to "Disabled" and click Ok.
Close the window.
Now you can try logging out or rebooting the computer to see if you have the options on the welcome screen, then logging in as a limited user and see if it worked there. It should also be gone from the lock screen.
Edit: Edited to remove shutdown from welcome screen. Thanks for the reminder, 'Problem Solved.'