Basically, such functionality is not supported out of the box. One option which you can try is manually hiding the items. Such an approach is demonstrated by the code snippet below:
void RadChart1_BeforeLayout(object sender, EventArgs e)
foreach (ChartAxisItem item in RadChart1.PlotArea.YAxis.Items)
item.Visible = false;
I hope this gets you started properly.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed