Executing generated script from output
You'd copy and paste the commands and then run them.  If you want to do this in a single step, you can write a small PL/SQL block

BEGIN
  FOR s IN (SELECT *
              FROM v$session ao 
             where (length(trim(ao.username)) = 5 
               and upper(substr(trim(ao.username),1,1)) = 'E')
  LOOP
    EXECUTE IMMEDIATE  'ALTER SYSTEM KILL SESSION '||
                         CHR(39)|| s.SID ||',' || s.SERIAL# ||CHR(39) || 
                         ' IMMEDIATE';
  END LOOP;
END;