It may be required to set flashback off temporarily
- To remove flashback log files to gain space in the flash recovery area
- To import schemas without generating flashback log files

Flashback cannot be disabled on a standby database that is in the state 'APPLY-ON'

Steps to set flashback off
Primary
1. dgmgrl
2. connect as sys
3. edit database sby set state='APPLY-OFF';
4. sqlplus / as sysdba
5. alter database set flashback off;
6. select flashback_on from v$database;  --check status

Standby
1. sqlplus / as sysdba
2. alter database set flashback off;
3. select flashback_on from v$database;  --check status

Primary and Standby (if flashback required)
1. alter database set flashback on;
2. select flashback_on from v$database;  --check status

Primary1. dgmgrl
2. connect as sys
3. edit database sby set state='APPLY-ON';
4. show configuration;