Turn Off Archive log mode

Once the Oracle database in archivelog mode can be turned off with the following steps:

Shutdown the database
shutdown immediate;

Change the parameter log_archive_start=false in pfile. This will stop the automatic archival of the database and the database administrator have to manually archive the
redo file for backup issuing alter system archive log all in archivelog mode;

Start the database in mount mode
startup mount;

Alter the database in noarchivelog mode. This will change the database mode to noarchive log mode such that redo log files can be overwritten before they are archived.
alter database noarchivelog;

Open the database
alter database open;

Verify the database status
archive log list;