In order to change the system domain, please login to your Partner portal <http://www.businesscatalyst.com/Admin/Index.aspx?to=PartnerPortal> -> Go to the Clients tab -> Select the site to change the URL for -> and click on the [Change] link for System and Secure URL's.
However, I see that ohcali.businesscatalyst.com is a Partner site under a Free Partner plan. So you won't see that site under the Clients tab. In this case, please submit a support ticket in order to get it changed.
Thank you. I will do that.