You can purge Unified Audit Trail by specifying last_arch_timestamp (If you don’t want to purge all Unified Audit Record),

BEGIN

DBMS_AUDIT_MGMT.SET_LAST_ARCHIVE_TIMESTAMP(audit_trail_type => DBMS_AUDIT_MGMT.AUDIT_TRAIL_OS,last_archive_time => TO_TIMESTAMP(’10-SEP-0714:10:10.0′,’DD-MON-RRHH24:MI:SS.FF’));

END;

/

BEGIN DBMS_AUDIT_MGMT.CLEAN_AUDIT_TRAIL(

audit_trail_type         =>  DBMS_AUDIT_MGMT.AUDIT_TRAIL_UNIFIED,

use_last_arch_timestamp  =>  TRUE);

END;

/