flashback log file deletion

1) how can i delete  old flashback log file dynamically?2) will it be problem to delete old flashback log file?
3) is it require to shutdown the database while deleting the old flashback log file.

we have set flash_recovery_area 550 GB we are facing space problem so we have to optimize it.

your expert suggestion will be of grate help


i have implemented the following things---

suppose today is 1st feb while running shell script it will remove flashback log 31stjan ...

i have set retention policy 1 days.

following is the my sh script
=====================

#!/bin/sh
#
# Daily Backup
#

. oraenv.oratest

export NLS_DATE_FORMAT="Dy DD-Mon-YYYY HH24:MI:SS"