If this per-machine system policy is set to 1, patches cannot be removed from the computer by a user or an administrator. The Windows Installer can still remove a patch that is no longer applicable to a product. If this policy is not set, a user can remove a patch from the computer only if the user has been granted privileges to remove the patch. This can depend on whether the user is an administrator, whether DisableMsi and AlwaysInstallElevated policy settings are set, and whether the patch was installed in a per-user managed, per-user unmanaged, or per-machine context.
Build date: 11/30/2012