removeClass not being applied

Question

On below I am opening thumb in preview above and then have image opening in a colorbox.

$('.picthumb').on('click', function(event){
    var $pic = $(this).find('img');
    $('.piclg').attr('src',$pic.attr('src'));
    $('.picthumb .selected').removeClass('selected');
    $(this).addClass('selected');
    $(".picthumb").removeClass('cboxElement');
});

<div class="piclg"></div>
<div class="picthumb"></div>    

Picthumb is a row of thumbnails which I am trying to remove the cboxelement with no success. Currently clicking on thumb opens modal. As well clicking on piclg opens modal. If I disable Colorbox thumb opens the piclg fine. Goal is to click thumb, open in piclg and then in larger Colorbox modal on click.

Hope the above makes sense. Would appreciate pointers to sort this. Thanks.