1. Log into your SiteWorx account. (eg: www.example.com:2443/siteworx/ )
2. Under SiteWorx Menu, click the Hosting Features menu item if it is not already open.
3. Click the Domain menu item and then click on the Secondary option.
Under Existing Domains
tab, Select Appropriate domain name you want to delete.
Click the Delete
A confirmation window will appear, Again click on the Delete
You should see a success message notifying you that your Secondary domain has been removed.