My functions.php file

You can adapt to your needs

// Remove query string from static files
function remove_cssjs_ver( $src ) {
 if( strpos( $src, '?ver=' ) )
 $src = remove_query_arg( 'ver', $src );
 return $src;
}
add_filter( 'style_loader_src', 'remove_cssjs_ver', 10, 2 );
add_filter( 'script_loader_src', 'remove_cssjs_ver', 10, 2 );

// Admin footer modification

function remove_footer_admin ()
{
    echo '<span id="footer-thankyou"><a href="https://www.topserve.com.ng" target="_blank"><img src="https://exclusively9ja.com/wp-content/uploads/2015/03/logo1.png" alt="Exclusively9ja" width="100"/></a></span><style>#wpfooter{background-color:#ffffff !important}#footer-upgrade{display:none}</style>';
}
add_filter('admin_footer_text', 'remove_footer_admin');

// remove URL field comment form
function crunchify_disable_comment_url($fields) {
    unset($fields['url']);
    return $fields;
}
add_filter('comment_form_default_fields','crunchify_disable_comment_url');

//to add defer to loading of scripts - and use defer to keep loading order
function script_tag_defer($tag, $handle) {
    if (is_admin()){
        return $tag;
    }
    if (strpos($tag, '://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js')) {
      return $tag;
    }
    if (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE 9.') !==false) {
	return str_replace(' src',' defer src', $tag);
    }
    else {
        return str_replace(' src',' defer src', $tag);
    }
}
add_filter('script_loader_tag', 'script_tag_defer',10,2);

//remove google font
add_action( 'wp_enqueue_scripts', 'remove_default_stylesheet', 20 );

function remove_default_stylesheet() {
     wp_dequeue_style( 'js_composer_front' );
    wp_deregister_style( 'js_composer_front' );
}

See Exclusively9ja.com for site in use