Hi Eddie,
I'm afraid you can't prevent CBD from trying to access the switches with the username and password. Quite a lot of the supported functionality requires the web interface to operate, so turning off web access would significantly limit what you can do. We don't have any plans to be able to turn individual protocols on or off for devices, though there is some work being done to allow you more control over which devices will be managed. Depending on what you are trying to achieve, this might help, but based on your comment about snmp working well, I think it probably will not help.
Cheers,
Dave.