Hi!
I see you are using the elementor posts widget. For that case the close button intentionally does not clear the container, it only clears the search phrase.
There might be however a way to do it via a minor custom code snippet.
add_action('wp_footer', 'wp_footer_asp_try_close', 9999);
function wp_footer_asp_try_close() {
?>
<script>
(function($){
$('.proclose').on('click mouseup touchend', function(e){
$('.asp_es_4 .elementor-posts-container').html('');
});
})(jQuery);
</script>
<?php
}
Try adding this code to the functions.php file in your theme/child theme directory – make sure to have a full server back-up first for safety. For more details you can check the safe coding guidelines.