How to null log_archive_dest parameter

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In this case if database are archive log mode database will send archive log file in DB_RECOVERY_FILE_DEST (Value of this Parameter).
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SQL> ALTER SYSTEM SET log_archive_dest_2='' SCOPE=BOTH;

System altered.

SQL> ALTER SYSTEM SET log_archive_dest_3='' SCOPE=BOTH;

System altered.

SQL> ALTER SYSTEM SET log_archive_dest_4='' SCOPE=BOTH;

System altered.