You can set a hidden input and on click of it show the datetimepicker like:
HTML:
<a class="calender-button" href="#">
Click Here
</a>
<input type="hidden" id="yourField" />
JS:
$('#yourField').datetimepicker();
$('.calender-button').click(function (e) {
e.preventDefault();
$('#yourField').data("DateTimePicker").toggle();
});