How can resize redo log ?

hi, i want how can resize redo log size,
i have try resize redo log file following way
1] first i have my redo log size is
GROUP# STATUS MEMBER SIZE
3 ONLINE /oradata/xyz/redo03.log 100M
2 ONLINE /oradata/xyz/redo02.log 100M
1 ONLINE /oradata/xyz/redo01.log 100M
I want this size is reducing , i have try following way
1] first i have create GROUP 4 add member
ALTER DATABASE ADD LOGFILE GROUP 4 ('/oradata/xyz/redo04.log') SIZE 30M;
then
alter system switch logfile;
in this way i have create remaning two redo log,
after create i have delete old redo log, is is correct method for reducing redo log.

Check Note: 1035935.6 - Example of How To Resize the Online Redo Logfiles
https://metalink.oracle.com/metalink/plsql/ml2_documents.showDocument?p_database_id=NOT&p_id=1035935.6

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    To drop an online redo log group, you must have the ALTER DATABASE system privilege. Before dropping an online redo log group, consider the following restrictions and precautions:
    * An instance requires at least two groups of online redo log files, regardless of the number of members in the groups. (A group is one or more members.)
    * You can drop an online redo log group only if it is inactive. If you need to drop the current group, first force a log switch to occur.
    * Make sure an online redo log group is archived (if archiving is enabled) before dropping it. To see whether this has happened, use the V$LOG view.
    SELECT GROUP#, ARCHIVED, STATUS FROM V$LOG;
    GROUP# ARC STATUS
    1 YES ACTIVE
    2 NO CURRENT
    3 YES INACTIVE
    4 YES INACTIVE
    Drop an online redo log group with the SQL statement ALTER DATABASE with the DROP LOGFILE clause.
    The following statement drops redo log group number 3:
    ALTER DATABASE DROP LOGFILE GROUP 3;
    When an online redo log group is dropped from the database, and you are not using the Oracle Managed Files feature, the operating system files are not deleted from disk. Rather, the control files of the associated database are updated to drop the members of the group from the database structure. After dropping an online redo log group, make sure that the drop completed successfully, and then use the appropriate operating system command to delete the dropped online redo log files.
    When using Oracle-managed files, the cleanup of operating systems files is done automatically for you.
    Your Database wont be affected as you can operate with 2 redo log files in each group as The minimum number of redo log files required in a database is two because the LGWR (log writer) process writes to the redo log files in a circular manner. so the process will hang becuase you are having 2 only groups if you want to remove 1 add a third one and make it the current group then remove the one you want to be offline.
    Please refer to:
    http://download.oracle.com/docs/cd/B10500_01/server.920/a96521/onlineredo.htm#7438
    Kind regards
    Mohamed
    Oracle DBA

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