Oracle 11gR2 Disabling Fast Recovery Area (FRA)

Disabling the Fast Recovery Area

If Flashback Database is enabled, then disable it before you disable the fast recovery area.
ALTER DATABASE FLASHBACK OFF;
If you are using fast recovery area for archive logs, then set the initialization parameter LOG_ARCHIVE_DEST_n to use a non-fast recovery area location.
eg.
LOG_ARCHIVE_DEST_1='LOCATION=USE_DB_RECOVERY_FILE_DEST'
ALTER SYSTEM SET LOG_ARCHIVE_DEST_1='LOCATION=/ORACLE/DBS/';

Disable the fast recovery area initialization parameter.
ALTER SYSTEM SET DB_RECOVERY_FILE_DEST='';

(From Oracle Database Backup and Recovery User's Guide)