run this script to find out OSPID

select substr(s.sid,1,3) sid,substr(s.serial#,1,5) ser,
substr(osuser,1,8) osuser,spid ospid,
substr(status,1,3) stat,substr(command,1,3) com,
substr(schemaname,1,10) schema,
substr(type,1,3) typ,
substr(decode((consistent_gets+block_gets),0,'None',
(100*(consistent_gets+block_gets-physical_reads)/
(consistent_gets+block_gets))
),1,4) "%HIT",value CPU,
substr(block_changes,1,5) bchng,
substr(consistent_changes,1,5) cchng
from v$process p, v$SESSTAT t,v$sess_io i ,v$session s
where i.sid=s.sid and p.addr=paddr(+) and s.sid=t.sid and
t.statistic#=12



once you got the OSPID, do the following command

ORAKILL SID_NAME OSPID