By locking all taskbar settings, you still can access the Taskbar Properties window where only the Jump Lists tab shows. Further speaking, if you would like to directly stop any user from opening Taskbar Properties to make any changes, you can enable related setting in the Local Group Policy Editor. For more information, please see below.
Video guide on how to prevent changes to taskbar and start menu settings in Windows 8:
Step 1: Open the Local Group Policy Editor.
Step 2: Find and open the setting named "Prevent changes to Taskbar and Start Menu Settings".
Follow the path of User Configuration/Administrative Templates/Start Menu and Taskbar, and you can easily find Prevent changes to Taskbar and Start Menu Settings.
Step 3: Make sure the setting is enabled.
That is, in the setting window, choose Enabled and tap OK.
From now on, when you open the Taskbar Properties, the following Restrictions window will appear, with a message that reads, "This operation has been cancelled due to restrictions in effect on this computer. Please contact your system administrator."
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