At present the deletion process, as you have found, is per single application. Based on your feedback we have noted this as a potential enhancement for a future release of the e-z Cert system to allow multi-delete on the Application list.
On this occasion we would be happy to assist you by deleting applications from your account, perhaps based on the submission date. If you email us at firstname.lastname@example.org stating the date range you need to be removed we'll undertake this for you.
e-z Cert Support Team.