In Océ Express WebTools you can close or delete a Smart Inbox in the [Jobs] tab - Smart Inbox section.
NOTE
When you delete a Smart Inbox, you only delete the view on the Smart Inbox, but not the content. To permanently delete the jobs from a Smart Inbox you must select the jobs in the Smart Inbox and click [Delete].
The default 'Public' Smart Inbox cannot be deleted, and will always be present.