As we have already discussed, often preferences will leave themselves in place after a computer or user falls out of scope of receiving that preference setting. For example, if someone changes OUs and therefore no longer receives a GPO that they used to, and that GPO setting contained some preferences, typically those preferences stick around on the machine to which they were applied because Group Policy does not actively remove them. However, checking this box inside the Common tab forces Group Policy to do just that – when the machine moves out of scope, it will remove this preference setting when it is no longer applicable. Usually this is exactly the behavior you are looking for when you check this box, but make sure to think through the ramifications of yanking out preference settings. There is certainly potential to cause some big problems.

Think about a registry key that you have plugged into place by using a Group Policy Preference, and you marked that preference to Remove this item when it is no longer applied. In this case, when the GPO no longer filters to you or your workstation, the registry key will be deleted. This behavior might be exactly what you are looking for, or perhaps what your preference actually did originally was to update an existing registry key to a more preferred setting. Your GPO will not know how to set that registry key back to default settings, and by removing the regkey entirely, you could break your application altogether. Or maybe you have modified and would now be removing a registry key that is important to Windows itself. Checking the box to remove this item when no longer applied could actually turn out to be detrimental to your operating system. Just make sure you take the time to think through each scenario when you select this checkbox.