DataGridTableStyle ColHidStyle = new DataGridTableStyle();

ColHidStyle.MappingName = "HideTest";

dataGrid1.TableStyles.Add(ColHidStyle);

ColHidStyle.GridColumnStyles["Modifier"].Width = 0;

// Below is an alternate approach

objDs.Tables["myTableName"].Columns["myColumnName"].ColumnMapping = MappingType.Hidden;