I set the valueName "DenyUnspecified"=1 in the Registry "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\DeviceInstall\Restrictions", It's same with the "Prevent installation of devices not described by other policy settings" in Group Policy "Computer Configuration/Administrative Templates/System/Device Installation/Device Installation Restrictions", this settings works well and prevents the new devices to be installed.

My problem is how to cancel this settings in Registry? After I set "DenyUnspecified"=0 or delete this valuename, the new devices could not be installed yet even restart my PC. If I open Group Policy, click the "enable" for "Prevent installation of devices not described by other policy settings", then click the "Not configured" and click "Apply", the new devices can be installed. Why can not I cancel the settings by setting "DenyUnspecified"=0 or delete this valuename in Registry?

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I have solved this problem, after set the valuename, run the command "gpupdate /force", this will cancel the setting.