Mitch Tulloch wrote,
You created a custom ADM file to push a registry setting to some machines, and it tattooed the registry of the targeted machines as a result. Now you want to reverse this by pruning the registry setting from the registry.pol file of the GPO. How can you do this?
Use PowerShell as follows:
Remove-GPRegistryValue -Name NAME -Key KEY -valueName POLICY
Where NAME is the name of the GPO, KEY is the Registry key you need to modify, and POLICY is the name of the registry value you want to remove.
This could resolve Windows 8 Metro Apps GPO issue J