@Override
 public ResultMessage delete(DriverPO po) {
   // TODO Auto-generated method stub
   String sql = "DELETE FROM driverpo WHERE idNumber='" + po.getIdNumber() + "';";
   ResultMessage result = Helper.delete(sql);
   return result;
 }
 @Override
 public ResultMessage delete(String id) {
   // TODO Auto-generated method stub
   String sql = "DELETE FROM driverpo WHERE workNumber='" + id + "';";
   ResultMessage result = Helper.delete(sql);
   return result;
 }
  @Override
  public ResultMessage deleteReceiptsPO(String date, String courier) throws RemoteException {
    // TODO Auto-generated method stub

    String sql = "delete from receiptspo where data='" + date + "' and courier='" + courier + "';";
    return Helper.delete(sql);
  }