There are a lot of things that WordPress adds to the head of your site. These can all be removed using the remove_action function that WordPress provides in your functions.php file.

<?php

//
// Removing WordPress Header Junk
//
// Place the following code in your `functions.php` file of your WordPress theme
// to remove some useless things from the head of your site.
// 
// http://scotch.io/quick-tips/cms/wordpress/removing-wordpress-header-junk
//

remove_action('wp_head', 'rsd_link'); // remove really simple discovery link
remove_action('wp_head', 'wp_generator'); // remove wordpress version

remove_action('wp_head', 'feed_links', 2); // remove rss feed links (make sure you add them in yourself if youre using feedblitz or an rss service)
remove_action('wp_head', 'feed_links_extra', 3); // removes all extra rss feed links

remove_action('wp_head', 'index_rel_link'); // remove link to index page
remove_action('wp_head', 'wlwmanifest_link'); // remove wlwmanifest.xml (needed to support windows live writer)

remove_action('wp_head', 'start_post_rel_link', 10, 0); // remove random post link
remove_action('wp_head', 'parent_post_rel_link', 10, 0); // remove parent post link
remove_action('wp_head', 'adjacent_posts_rel_link', 10, 0); // remove the next and previous post links
remove_action('wp_head', 'adjacent_posts_rel_link_wp_head', 10, 0 );

remove_action('wp_head', 'wp_shortlink_wp_head', 10, 0 );

?>