How to reclaim space from flash recovery area

 Hi,
I'm looking at claiming some space back from the 'FLASHBACK' area:

4) Filetype Summary

TYPE               FILES       BLOCKS      USED_MiB     SPACE_MiB
---------------- ------- ------------ ------------- -------------
ARCHIVELOG         2,526   27,951,061      13,648.0      14,748.6
BACKUPSET          1,175    4,603,621       2,247.9       3,021.0
CONTROLFILE            3        7,107         111.0         120.9
DATAFILE              57    3,035,747      23,716.8      23,791.8
FLASHBACK          3,448    5,159,198      40,306.2      53,150.1
ONLINELOG             14      942,094         460.0         543.5
PARAMETERFILE          8           64            .0           8.0
TEMPFILE               3       43,523         340.0         345.7
                                      ------------- -------------
Total :                                    80,830.0      95,729.5

8 rows selected.

On querying the database for v$flash_recovery_area_usage, it shows there's ~ 34% space that's reclaimable. How can I achieve this? I've verified that there are obsolete archive logs by 'rman crosscheck'. Are there any other ways I can reclaim this space?

SQL> select PERCENT_SPACE_USED,PERCENT_SPACE_RECLAIMABLE, NUMBER_OF_FILES from v$flash_recovery_area_usage where FILE_TYPE like 'FLASHBACK LOG';