private void btnRemove_Click(object sender, EventArgs e)
        {
            int indx = listBooks.SelectedIndex;

            b.RemoveBook(result[indx].ISBN);
            listBooks.Items.RemoveAt(indx);
        }
 private void RB_Click(object sender, EventArgs e)
 {
     try
     {
         int indx = CB.SelectedIndex;
         owner.RemoveBook(current[indx].ISBN);
         CB.Items.RemoveAt(indx);
     }
     catch
     {
         MessageBox.Show("No Books To Remove");
     }
 }