Remove access to the context menus for the taskbar Hides the menus that appear when you right-click the taskbar and items on the taskbar, such as the Start button, the clock, and the taskbar buttons. This setting does not prevent users from using other methods to issue the commands that appear on these menus.

(1) GPO: User Configuration\Administrative Templates\Start Menu and Taskbar!Remove access to the context menus for the taskbar (2) REG: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer!NoTrayContextMenu