Hi ThemeVan,
I had the same problem. I hunted down the register name which was in includes/class.yith-wcwl-init.php.
Add this to your functions.php file and it will remove the Yith version:
function dequeue_yith_font_awesome_css() {
wp_dequeue_style('yith-wcwl-font-awesome');
wp_deregister_style('yith-wcwl-font-awesome');
}
add_action('wp_enqueue_scripts','dequeue_yith_font_awesome_css', 100);