Hiding your applicants' records from your Dashboard doesn't delete them.
You can always find the records under Properties > Manage Occupants but you cannot "unhide" them to appear at the Dashboard again.
You can simply search for the applicant's name using the search bar in the right upper corner.
The record cannot be manually brought back up to your Dashboard but it will automatically reappear if its status changes. For example, if you hid an applicant with status "Background Check in Progress", after his authorization he will re-appear on Dashboard with status "Review Screening Reports".