Hi Thomas,
Thank you for writing.
Currently, RadPdfViewer does not have a feature for unloading documents. I will add this as a feature request in our Public Issue Tracking System. Feel free to add your vote for it here:
http://www.telerik.com/support/pits.aspx#/public/winforms/14400.
Your
Telerik Points have been updated for this report.
For the time being, you can add a new menu item in the context menu for example ("Close") and when it is clicked, you can load an empty pdf file like the one attached.
I hope that you find this information useful
Regards,
Stefan
the Telerik team