Hello Syed Danish,
Supposing your RadOutlookBar is named "outlookBar" and it is populated declaratively, you should clear its Items with :
But you cannot use this approach if your outlookbar is databound. In this case you can use:
If this doesn`t fit in your scenario we would highly appreciate if you send us a runnable sample showing the issue you have come up with. Thank you in advance.
the Telerik team
Browse the videos here>>
to help you get started with RadControls for Silverlight