Best way to delete oracle flashback logs

The deletion of flashback logs is handled internally, which means you should not delete the flashback logs manually unless you disable the FLASHBACK DATABASE

According to the Oracle Documentation, flashback log files are deleted automatically when:

1. If the flash recovery area is full, then an archived redo log may be automatically deleted by the flash recovery area to make space for other files. In such a case, any flashback logs that would require the use of that redo log file for the use of FLASHBACK DATABASE are also deleted.
   
2. If the database needs to create a new flashback log and the flash recovery area is full or there is no disk space, then the oldest flashback log is reused instead.

Make sure there aren't any guaranteed restore points in place, causing flashback logs to be retained longer than they should. Use this query to check:

select * from v$restore_point;