1. Define a class that implements IUIElementCreationFilter:
   
   class NoHeaderCreationFilter : IUIElementCreationFilter
   {
       public void AfterCreateChildElements(UIElement parent)
       {
           if (parent is UltraListViewUIElement && (parent.Control as UltraListView).View == UltraListViewStyle.Details)
           {
               UIElement header = parent.ChildElements[0];
               UIElement list = parent.ChildElements[1];
   
               Rectangle rc = Rectangle.Union(header.Rect, list.Rect);
               list.Rect = rc;
   
               rc.Height = 0;
               header.Rect = rc;
           }
       }
   
       public bool BeforeCreateChildElements(UIElement parent)
       {
           return false;
       }
   }
   
   
   
2. Set your UltraListView to use this class:
   
   myListView..CreationFilter = new NoHeaderCreationFilter();

I ran into same problem and hopefully it will be a new feature in one of the next releases.

In the meantime i followed this workaround to hide the header with this code:

        lstInfo.View = UltraWinListView.UltraListViewStyle.Details

        With lstInfo.ViewSettingsDetails

            .ColumnHeaderStyle = HeaderStyle.Standard
            .ColumnHeaderBorderStyle = UIElementBorderStyle.None
            .ColumnHeaderAppearance.BackColor = Color.Transparent
            .AllowColumnSizing = False
            .AllowColumnSorting = False

        End With

Assuming you are using the 'Details' setting of the View property, you cannot hide the header. Going by the screenshot it would appear that you only have one column, so you should use set the View property to 'List', and if you want only one column of items, set the UltraListView.ViewSettingsList.MultiColumn property to false.