The item currently being processed is identified by the event parameter's MenuItem property. It's visibility is controlled by the Add property. Set this property to false to hide the item from the menu.
This example demonstrates how to prevent end-users from hiding field headers. To do this, the ASPxPivotGrid.AddPopupMenuItem event is handled. If the processed item is the 'Hide' menu item, it is not added to the field header's context menu.