SQL> select group#,bytes/1024/1024 MB ,status from v$log
  2  /
 
    GROUP#         MB STATUS
---------- ---------- ----------------
         1         10 ACTIVE
         2         10 CURRENT
         3         10 INACTIVE
 
SQL> select * from v$logfile;
 
    GROUP# STATUS  TYPE    MEMBER                                                                           IS_RECOVERY_DEST_FILE
---------- ------- ------- -------------------------------------------------------------------------------- ---------------------
         1         ONLINE  /bases/oracle/oradata/CTMMS/redo01.log                                           NO
         2         ONLINE  /bases/oracle/oradata/CTMMS/redo02.log                                           NO
         3         ONLINE  /bases/oracle/oradata/CTMMS/redo03.log                                           NO
 
SQL> alter database add logfile group 4 ('/bases/oracle/oradata/CTMMS/redo04.log') size 512M;
 
Database altered
 
SQL> alter database add logfile group 5 ('/bases/oracle/oradata/CTMMS/redo05.log') size 512M;
 
Database altered
 
SQL> alter database add logfile group 6 ('/bases/oracle/oradata/CTMMS/redo06.log') size 512M;
 
Database altered
 
SQL> select group#,bytes/1024/1024 MB ,status from v$log
  2  /
 
    GROUP#         MB STATUS
---------- ---------- ----------------
         1         10 INACTIVE
         2         10 ACTIVE
         3         10 INACTIVE
         4        512 CURRENT
         5        512 UNUSED
         6        512 UNUSED
 
6 rows selected
 
SQL>
SQL> alter database drop logfile group 1;
 
Database altered
 
SQL> select * from v$logfile;
 
    GROUP# STATUS  TYPE    MEMBER                                                                           IS_RECOVERY_DEST_FILE
---------- ------- ------- -------------------------------------------------------------------------------- ---------------------
         2         ONLINE  /bases/oracle/oradata/CTMMS/redo02.log                                           NO
         3         ONLINE  /bases/oracle/oradata/CTMMS/redo03.log                                           NO
         4         ONLINE  /bases/oracle/oradata/CTMMS/redo04.log                                           NO
         5         ONLINE  /bases/oracle/oradata/CTMMS/redo05.log                                           NO
         6         ONLINE  /bases/oracle/oradata/CTMMS/redo06.log                                           NO
 
SQL> select group#,bytes/1024/1024 MB ,status from v$log
  2  /
 
    GROUP#         MB STATUS
---------- ---------- ----------------
         2         10 ACTIVE
         3         10 INACTIVE
         4        512 CURRENT
         5        512 UNUSED
         6        512 UNUSED
 
SQL> alter system switch logfile;
 
System altered
 
SQL>  select group#,bytes/1024/1024 MB ,status from v$log;
 
    GROUP#         MB STATUS
---------- ---------- ----------------
         2         10 INACTIVE
         3         10 INACTIVE
         4        512 ACTIVE
         5        512 CURRENT
         6        512 UNUSED
 
SQL> alter database drop logfile group 2;
 
Database altered
 
SQL> alter database drop logfile group 3;
 
Database altered