DECLARE
  -- Replace XXX by your pattern
  user_pattern all_users.username%TYPE := 'XXX_%';
BEGIN

  FOR rec IN (SELECT SID
                FROM v$session
               WHERE username LIKE user_pattern)
  LOOP
    EXECUTE IMMEDIATE 'ALTER SYSTEM DISCONNECT SESSION ' || rec.SID || ' IMMEDIATE';
  END LOOP;

  FOR rec IN (SELECT username
                FROM all_users
               WHERE username LIKE user_pattern)
  LOOP
    EXECUTE IMMEDIATE 'DROP USER "' || rec.username || '" CASCADE';
    EXECUTE IMMEDIATE 'DROP TABLESPACE "' || rec.username || '" INCLUDING CONTENTS AND DATAFILES CASCADE CONSTRAINTS';
  END LOOP;
END;
/