I don't know of a way to disable the Windows Explorer Address Bar in a GPO, but I found this registry edit you can try.
Remove address bar from windows explorer
Hi,
I got a requirment to hide Hide or Disable Windows Explorer Address Bar for Windows 7 clients. I went through some article posted in some forums but those did not help me acheive my requirment. Since by using address bar and search bar users can access network resources by typing network address. it become a headache for company operations. So i need to hide or disable it. Appriciate your quick response.
I had another requirement to hide Network icon from navigation pane. Seems these requirements cannot fulfill by using GPO’s I followed below steps to hide network from nivigation pane,
Network - Add or Remove from Navigation Pane - Windows 7 Forums
Thank You,
Dilshan
I don't know of a way to disable the Windows Explorer Address Bar in a GPO, but I found this registry edit you can try.
Remove address bar from windows explorer