how to delete a selected item from a row?

Code:

DialogResult result3 = MessageBox.Show("Proceed With Checkout?", "Request Granted",
MessageBoxButtons.YesNo,
MessageBoxIcon.Question,
MessageBoxDefaultButton.Button2);

            if (result3 == DialogResult.Yes)
            {
                int quantity = Int32.Parse(quantityTextBox.Text);
                if (quantity ==1)
                {
                    this.BindingContext[iTEMDataSet, "ITEM"].RemoveAt(this.BindingContext[iTEMDataSet, "ITEM"].Position);
                }
                else if (quantity > 1)
                {
                    quantity = quantity - 1;
                    quantityTextBox.Text = Convert.ToString(quantity);
                    //update database here.
                }

            }
            if (result3 == DialogResult.No)
            {
                //quantity = quantity - 1;
                //quantityTextBox.Text = Convert.ToString(quantity);
            }
        }
        catch
        {
            MessageBox.Show("error!");
        }
    }

//As you can see this program allows you to deleted the quantity of an item in a row , but if the quantity = 1 , the item in the top most row will be deleted instead of the selected row.

I changed 'RemoveAt(this.BindingContext[iTEMDataSet, "ITEM"].Position); but to no avail .

Thanks for the help guys ^^