Dropping connected users to an Oracle database, taken from http://stackoverflow.com/questions/85804/dropping-a-connected-user-from-an-oracle-10g-database-schema

gistfile1.sql

SELECT s.inst_id,
       s.sid,
       s.serial#,
       p.spid,
       s.username,
       s.program
FROM   gv$session s
       JOIN gv$process p ON p.addr = s.paddr AND p.inst_id = s.inst_id
WHERE  s.type != 'BACKGROUND';

gistfile2.sql

ALTER SYSTEM KILL SESSION '<s.sid>,<s.serial#>';