Imports Infragistics.UltraChart.Data.Series ... CType(Me.ultraChart1.Series(0), SeriesBase).Visible = False
Starting in the 2006 Volume 3 release, you can choose to display or hide a specific series on a chart (composite or non-composite) by simply toggling its Visible property.
In Visual Basic:
Imports Infragistics.UltraChart.Data.Series ... CType(Me.ultraChart1.Series(0), SeriesBase).Visible = False
In C#:
using Infragistics.UltraChart.Data.Series; ... ((SeriesBase)this.ultraChart1.Series[0]).Visible = false;