Changing The Selected Item In A Select Box

I am adding logic to a product to hide an option and reshow it based on some choices. However, after I hide and reshow, my textbox has an extra item added and selected "Please, select one". Either, how can I get rid of that option, or how can I change the option to the first variant defined in the product? Here is my code, which I inherited from a previous developer (open to suggestions on how to do this better):

var cover_labels = $("#op_option_pages").find("label:contains('Scratch and Dent')");
var cover_label = null;
for(var i=0, len = cover_labels.length; i
if(cover_labels.eq(i).text().length <= 18) {
cover_label = cover_labels.eq(i);
break;
}
}
if(cover_label) {
var cover_page = cover_label.closest('.op-page');
var cover_option = cover_page.find('#' + cover_label.attr('for') + ' option:selected');
if(cover_option.length) {
var cover_text = cover_option.text();
if(displayscratchanddent.indexOf("false") > -1)
{
cover_label.closest('.op-page-option').remove();
}
else
{
cover_label.addClass();
}
}
}