WP action and callback function to inject CSS into admin head and hide comment activity

WordPress: Hide Dashboard comment activity

function remove_dashboard_comment_activity() {
	echo '<style type="text/css">li.comment-count, li.comment-mod-count, #latest-comments, #wp-admin-bar-comments { display:none; }</style>';
}

add_action('admin_head', 'remove_dashboard_comment_activity');