There is no option to remove that.
You would have to edit the file administrator/components/com_hikashop/helpers/helper.php
Code:
$text = '<!-- HikaShop Component powered by '.$link.' -->
<!-- version '.$config->get('level').' : '.$config->get('version').' -->';
Note that if you remove it, we won't know the version/edition you're using on your website. So make sure that you specify it when asking a question.
