In order to set null value to UXDateTimePicker, please ensure that AllowNull property has been set to True. Once a date has been set, press Ctrl + A to select all of the text in the text box of UXDateTimePicker and then press Delete key.

This should help.

Thanks, that works.  However for the average user they would not know how to do this (unless every datetimepicker has instructions displayed next to them).

I would suggest that this needs to be part of the UI and have a 'Clear' button on the pop-up Calendar.

Thank you for your post suggesting addition of ‘Clear’ button on the pop-up calendar of UXDateTimePicker to set the value to null. I have forwarded this valuable feedback to ClientUI Development team and submit this as feature request under Task #1279.

Thanks again for your message.