如何在c＃中使用DbContext删除对象？

I have this delete method:

我有这个删除方法:

private void btnDeleteOrderLine_Click(object sender, EventArgs e)
{
    OrderLine orderLine = (OrderLine)dgvOrderLine.SelectedRows[0].DataBoundItem;
    db.OrderLines.Remove(orderLine);
    db.SaveChanges();
    refreshGrid();
}
privat