If there are unsuccessful candidates, how long do we keep their application data in the system?

Summary:

Hi,

 If there are unsuccessful candidates, how long do we keep their application data in the system?

Example: If the recruiter has rejected a candidate or the candidate has withdrawn his application, still the candidate has a candidate record in the ORC system.

According to customer requirement, they want to delete the unsuccessful candidates from the system older then 3 months or 6 months, how can we achieve this?