Force a specific background and accent color
Forces Windows to use the specified colors for the background and accent. The color values are specified in hex as #RGB.
By default, users can change the background and accent colors.
If this setting is enabled, the background and accent colors of Windows will be set to the specified colors and users cannot change those colors. This setting will
not be applied if the specified colors do not meet a contrast ratio of 2:1 with white text.
At least Windows Server 2012 R2, Windows 8.1 or Windows RT 8.1
Not Configured - No registry values are specified.
Disabled - Any values that would be created by the policy in the registry are deleted.
Enabled - Adding, modifying or delete values in the registry.
Force a specific background and accent color can be found in the Group Policy.
Please navigate to Computer Configuration - Policies - Administrative Templates - Control Panel - Personalization folder.