Can I remove iCal accounts via terminal?

I'd like to batch remove old CalDAV accounts from iCal for my users. We've switched mail service and no longer need these old accounts.

They were not installed via a profile (bummer) so it seems a shell script or terminal command is my only option.

Is it possible without completely resetting iCal? I'd like the users to be able to keep their personal calendars (local, iCloud, Google, etc.).