I have tried numerous things and nothing seems to be working.
I am using jQuery and Chosen plugin.
Methods I have tried:
var select = jQuery(
$('#autoship_option').val('').trigger('liszt:updated');
and set the default option value to ''.
It has to be used with chosen updated jQuery available at this link: https://raw.github.com/harvesthq/chosen/master/chosen/chosen.jquery.min.js.
I spent one full day to find out at the end that jquery.min is different from chosen.jquery.min