HOW-TO GPP Apply Once and Do Not Reapply

With Group Policy Preferences the settings "Apply Once and Do Not Reapply" can be enforced.

This is a great feature but when testing a GPP that you need to re-work and then re-test, it can be a bit annoying.

Instead of using another machine, you can clean your test machine as follow:

To know if a GPP has already been applied to a machine, the machine stores the Unique ID associated with each  "Apply Once" settings in the registry.

For USER settings the UIDs are stored under:
HKEY_CURRENT_USER\Software\Microsoft\Group Policy\Client\RunOnce

and for MACHINE settings under:
HKEY_LOCAL_MACHINE\Software\Microsoft\Group Policy\Client\RunOnce

To know which UID(s) to clear, take a backup of your GPO and search for the "FilterRunOnce" ID in the gpreport.xml file.