As the RadChart Series object is a collection of ChartSeriesItem
objects you can use the Remove() or RemoveAt() methods to remove a Chart Series Item from it. The other items will automatically reposition themselves to fill the vacant place so that vizually there won't be gaps (empty values).
the Telerik team
Q3’10 SP1 of RadControls for WinForms is available for download
; also available is the Q1'11 Roadmap
for Telerik Windows Forms controls.