^C & ^V from orafaq.com

One normally kills Oracle processes using the "alter system kill session" command. One can also use the orakill.exe command that comes with Oracle for NT/2000 to kill a thread. You need to specify the thread ID in Hex. Try orakill /? or orakill /h for more details. Example:

SQL> select spid as thread, osuser, s.program
SQL> from sys.v_$process p, sys.v_$session s
SQL> where p.addr = s.paddr;

DOS> orakill.exe sid thread

Sanjay