The preferred schedule to delete a protected database and its backups after you terminate the source database -
If you do not specify a value, then Recovery Service schedules to delete the protected database 72 hours (3 days) after the database is terminated.
If you set the option as DELETE_AFTER_RETENTION_PERIOD, then Recovery Service schedules to delete the protected database after the backup retention period expires.
The preferred schedule to delete a protected database and its backups after you terminate the source database -