Thank you for writing.
Yes, you can hide the borders of the desired controls. Here is how to do that:
((BorderPrimitive)radDropDownList1.DropDownListElement.Children).Visibility = ElementVisibility.Collapsed;
((BorderPrimitive)radDateTimePicker1.DateTimePickerElement.Children).Visibility = ElementVisibility.Collapsed;
Off topic, please do not post questions in threads that are not related to the initial subject of a thread. This thread concerns the border of RadTextBox
and should be used only for this subject., in order to allow the users searching for this information to find it easily. If you do not find a suitable thread, please open a new one. For more information regarding forum usage, please take a look at this thread: http://www.telerik.com/community/forums/winforms/editors/important-information-on-using-the-telerik-forums.aspx
I hope this helps.
All the best,
the Telerik team