There are several ways of doing this on Windows. (If anyone knows of any solutions for Linux or MacOS, please pass them on to me!)

On Windows, if you’re not a member of the Administrators group then (by default) you shouldn’t be able to change the system clock anyway. If you are able to change the clock, you could try one of these solutions:

Solution #1: Hide the clock from the Taskbar

Right-click on the Taskbar, select Taskbar settings, go to Date & time settings, and uncheck the option Show time and date in the system tray.

Easy to undo, of course, but adds an extra layer of inconvenience.

Solution #2: Change the permissions using the Group Policy Editor

• Select Run… from the Start Menu (or press Windows+R) and enter gpedit.msc as the program to open.
• Navigate to Computer Configuration / Windows Settings / Security Settings / Local Policies / User Rights Assignment.
• Edit the policy for Change the system time and remove from the list the Administrators group (and the Power Users group, if it’s there). Do not remove LOCAL SERVICE.
• Log off and log on again for the new permissions to take effect.

You can restore the original permissions by re-editing the policy and adding the Administrators group back to the list.

Note that the Group Policy Editor is not included in the Home Edition of Windows XP, Vista, and 7, in which case you could try…

Solution #3: Use an elevated command prompt

Go here for detailed instructions (scroll down to “Option Two”).