View and terminate Oracle Database user sessions

Verify sessions:
SELECT USERNAME FROM V$SESSION;

SELECT USERNAME, SID, SERIAL#, STATUS
  FROM V$SESSION
  WHERE USERNAME like 'SCOTT%';

Generate SQL to terminate sessions:
SELECT 'ALTER SYSTEM KILL SESSION ''' || SID || ',' || SERIAL# || ''';'
  FROM V$SESSION
  WHERE USERNAME like 'SCOTT%';