flashback logs not cleared

We have a 2 node RAC database (11202) and +FRA is 150 GB size. The flashback_retention_target=720. this is a standby database. we are getting error that so and so log cannot be archived. when I queried V$FLASHBACK_% views I found that the logs in +FRA is going back to 7th Mar 2014. How can I delete those logs and make space? How come we have logs for last 4 months when we have retention time of 12 hours?

lsdg from asmcmd say on 79MB free space. Could you please suggest some solution?

SQL> set pau on
select * from v$flashback_database_logfile order by first_time