How to permanently delete a row in oracle forever
There is likely a more streamlined set of steps, but here is a start.


Delete the data out of any materialized views or home grown
replication methods using triggers or the like. 
Delete the data out of any database audit tables. 
Change the database to noarchivelog.
Create a new undo tablespace. 
Switch log files until all are archived.
Shutdown the database.
Turn off and purge any storage or virtual machine level snapshot capability. 
Delete all trace files that may contain the data. 
Delete all backups sets including archive log backups that could contain the data. 
Delete all OS audit logs that could contain the data. 
Visit any computer that may have the data cached or displayed and destroy it there. 
Visit any other storage devices the data may have been copied to and purge those.
Find any hard copies of the data and destroy those. 
If someone memorized the data, memory erasure is beyond the scope of this site.