The purpose of this tutorial is to demonstrate you how to show and hide the RadDateTimePicker's content in code.
In order to do this you have to use the RadDateTimePicker's IsDropDownOpen boolean property. Whenever you set its value to True the content (the calendar and/or the clock) will be shown, otherwise setting its value to False will hide the content.
this.radDateTimePicker.IsDropDownOpen = true;
Me.radDateTimePicker.IsDropDownOpen = True