this.dataGridView.AllowUserToAddRows = false;
https://stackoverflow.com/questions/4212432/hide-the-extra-row-at-the-bottom-in-a-datagridview-in-a-winform-application
this.dataGridView.AllowUserToAddRows = false;
https://stackoverflow.com/questions/4212432/hide-the-extra-row-at-the-bottom-in-a-datagridview-in-a-winform-application