SQL> SELECT LPAD(' ',DECODE(l.xidusn,0,3,0)) || l.oracle_username "User Name",
o.owner, o.object_name, o.object_type , l.session_id
FROM v$locked_object l, dba_objects o
WHERE l.object_id = o.object_id
ORDER BY o.object_id, 1 DESC ;

SQL> SELECT session_id "sid",SERIAL# "Serial",
substr(object_name,1,20) "Object",
substr(os_user_name,1,10) "Terminal",
substr(oracle_username,1,10) "Locker",
nvl(lockwait,'active') "Wait",
decode(locked_mode,
2, 'row share',
3, 'row exclusive',
4, 'share',
5, 'share row exclusive',
6, 'exclusive', 'unknown') "Lockmode",
OBJECT_TYPE "Type"
FROM
SYS.V_$LOCKED_OBJECT A,
SYS.ALL_OBJECTS B,
SYS.V_$SESSION c
WHERE
A.OBJECT_ID = B.OBJECT_ID AND
C.SID = A.SESSION_ID
ORDER BY 1 ASC, 5 DESC;

SQL> SELECT sid,serial# FROM v$session
WHERE session_id = <session id FROM above query>;

SQL> ALTER SYSTEM KILL SESSION 'session-id, session-serial';