When the Archived Redo Log Deletion Policy Is Disabled ->
The archived redo log deletion policy is configured to NONE by default. In this case, RMAN considers archived redo log files in the recovery area as eligible for deletion if they meet both of the following conditions:
"The archived redo logs, whether in the flash recovery area or outside of it, have been transferred to the required remote destinations specified by LOG_ARCHIVE_DEST_n."
The archived redo logs have been backed up at least once to disk or SBT or the logs are obsolete according to the backup retention policy.