TAdvDBDateTimePicker does not support the use of empty date/time fields.

This is a limitation that is actually in the underlying Windows date/timepicker control that is used inside TAdvDBDateTimePicker. This Windows date/timepicker control doesn't offer the capability for entry of empty values and as such, we can't workaround this on TAdvDBDateTimePicker.

Our own custom control TDBPlannerDatePicker has this capability though as this is created fully in VCL and does not depend on a Windows control. See: https://www.tmssoftware.com/site/plannercal.asp