Algo como isso pode estar bem?
Set WshNetwork = WScript.CreateObject("WScript.Network")
Set clDrives = WshNetwork.EnumNetworkDrives
For i = 0 To clDrives.Count -1 Step 2
If clDrives.Item(i) <> "Z:" Then
WSHNetwork.RemoveNetworkDrive clDrives.Item(i), True, True
End If
Next