I create a radChartView with three bar series and a legend and show it on the form.
Then I change runtime programatically the appearance of the two series (I make them invisible: IsVisible = false), but the legend remains the same.
For comparison - in the MSChart such stupidity is not observed
By design, RadChartView doesn't hide the legend items if the associated series is hidden. However, it can be easily achieved. Here is demonstrated a sample code snippet: