jQuery UI datepicker reset date

Just add this code

}).keyup(function(e) {
    if(e.keyCode == 8 || e.keyCode == 46) {
        $.datepicker._clearDate(this);
    }
});

You can use backspace to clear field even if it has in read only mode. Source

Clear button in calendar.

 $("#txtCalendar").datepicker({
        showButtonPanel: true,
        closeText: 'Clear',
        onClose: function (dateText, obj) {
            if ($(window.event.srcElement).hasClass('ui-datepicker-close'))
                $("#txtCalendar").val('');
        }
    });

See http://codepen.io/alexgill/pen/yOQrwV

$(SELECTOR).datepicker('setDate', null);

The proper way to reset the date of a Datepicker widget is like this:

$.datepicker._clearDate('#input_field_goes_here');

Or like this:

$('#input_field_goes_here').datepicker('setDate', null);

Whichever works best for you.