Hello Fan Chen,

Thank you for contacting Infragistics. There is no native way to hide the Navigation Pane without retemplating the entire control. I recommend avoiding this since it will remove core functionality. Do you need it outright removed or to disabling it's click ability to fly-out the options? When it's removed do you want the control to shrink too?

If you want to hide the entire area it then you will need to retemplate the control by modifying the default styles. They are installed locally here:
C:\Program Files\Infragistics\NetAdvantage 20xx.x\WPF\DefaultStyles

To disable clicking, the best approach would be to handle the components SelectedGroupPopupOpening event and cancel it.

eg.

    private void xamOutlookBar1_SelectedGroupPopupOpening(object sender, Infragistics.Windows.OutlookBar.Events.OutlookBarCancelableRoutedEventArgs e)
        {
            e.Cancel = true;           
        }

Let me know if you have any questions regarding this matter.