Source:

		Platform: Linuxx86_64
		Server Name: RAC1.RAJASEKHAR.COM, IP: 192.168.2.101
		DB Version: Oracle 11.2.0.3, File system: ASM
		DB Name: APAC, DB_UNIQUE_NAME: APAC
		Flashback: Disabled
		Oracle Home Path: /u01/app/oracle/product/11.2.0/db_1
		
Target:
		
		Platform: Linuxx86_64
		Server Name: RAC2.RAJASEKHAR.COM, IP: 192.168.2.102
		DB Version: Oracle 11.2.0.3, , File system: ASM
		DB Name: APAC, DB_UNIQUE_NAME: EMEA
		Flashback: Disabled
		Oracle Home Path: /u01/app/oracle/product/11.2.0/db_1

SQL> select name, open_mode, database_role from v$database;

NAME      OPEN_MODE            DATABASE_ROLE
--------- -------------------- ----------------
APAC      READ ONLY WITH APPLY PHYSICAL STANDBY

SQL> select * from v$logfile;

    GROUP# STATUS  TYPE    MEMBER                                                       IS_
---------- ------- ------- ------------------------------------------------------------ ---
         3         ONLINE  /u01/app/oracle/oradata/emea/redo03.log                      NO
         2         ONLINE  /u01/app/oracle/oradata/emea/redo02.log                      NO
         1         ONLINE  /u01/app/oracle/oradata/emea/redo01.log                      NO
         4         STANDBY /u01/app/oracle/oradata/emea/redo04.log                      NO
         5         STANDBY /u01/app/oracle/oradata/emea/redo05.log                      NO
         6         STANDBY /u01/app/oracle/oradata/emea/redo06.log                      NO
         7         STANDBY /u01/app/oracle/oradata/emea/redo07.log                      NO

7 rows selected.

SQL>

SQL> alter database drop standby logfile group 4;
alter database drop standby logfile group 4
*
ERROR at line 1:
ORA-01156: recovery or flashback in progress may need access to files


SQL> alter database recover managed standby database cancel;

Database altered.

SQL> select name, open_mode, database_role from v$database;

NAME      OPEN_MODE            DATABASE_ROLE
--------- -------------------- ----------------
APAC      READ ONLY            PHYSICAL STANDBY

SQL> 

SQL> ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT='MANUAL';

System altered.

SQL>

SQL> alter database drop standby logfile group 4;
alter database drop standby logfile group 4
*
ERROR at line 1:
ORA-00261: log 4 of thread 1 is being archived or modified
ORA-00312: online log 4 thread 1: '/u01/app/oracle/oradata/emea/redo04.log'

SQL> 

Note: If the status of standby redolog show the "clearing_current" then we cannot drop "clearing_current" status logs,and for that we have to sync with Primary and clear the log first before dropping as below

SQL> alter database clear logfile group 4;

Database altered.

SQL> alter database drop standby logfile group 4;

Database altered.

SQL> alter database drop standby logfile group 5;

Database altered.

SQL> alter database drop standby logfile group 6;

Database altered.

SQL> alter database drop standby logfile group 7;

Database altered.

SQL> select * from v$logfile;

    GROUP# STATUS  TYPE    MEMBER                                                       IS_
---------- ------- ------- ------------------------------------------------------------ ---
         3         ONLINE  /u01/app/oracle/oradata/emea/redo03.log                      NO
         2         ONLINE  /u01/app/oracle/oradata/emea/redo02.log                      NO
         1         ONLINE  /u01/app/oracle/oradata/emea/redo01.log                      NO

SQL> select * from v$standby_log;

no rows selected

SQL>

SQL> ALTER SYSTEM SET STANDBY_FILE_MANAGEMENT='AUTO' SCOPE=BOTH;

System altered.

SQL>

SQL> alter database recover managed standby database disconnect from session;

Database altered.

SQL> select name, open_mode, database_role from v$database;

NAME      OPEN_MODE            DATABASE_ROLE
--------- -------------------- ----------------
APAC      READ ONLY WITH APPLY PHYSICAL STANDBY

SQL>