Run the following in SQL* Plus as SYS/SYSDBA user to terminate sessions.
** Update username with your schema name.
DECLARE
CURSOR c1 is
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'
and UPPER(s.username) = 'SCOTT';
BEGIN
FOR rec in c1 LOOP
EXECUTE IMMEDIATE 'ALTER SYSTEM KILL SESSION '''||rec.SID||','||rec.serial#||'''';
END LOOP;
END;
/
show errors;