Hiding columns by which the records are grouped
You can configure the view settings so that when you group the records by a column, this column is automatically hidden in the grid (the heading of this column is shown in the Group Panel).
To enable automatic hiding of columns by which the records are grouped:
Select View > Customize View from the main menu, the Customize View window opens.
Click the Options tab.
Under Grouping, select the Hide Columns on Grouping check box.