Navigate the the location below in your registry and make the corresponding change.

Create or edit the existing DWORD value named 'DontAddDefaultRoute' in the key below. 

Set the value to '1' to prevent the default route from being added to the routing table. 

Key:[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\**NIC Name**\Parameters]
Value Name: DontAddDefaultRoute
Data Type: REG_DWORD
Data:(0 = disable restriction, 1 = enable restriction)