If you dont want to use a plugin for removing tags from your wp_head you can copy/paste those functions you need and to put them in your themes functions.php file.

// Really Simple Discovery
remove_action('wp_head', 'rsd_link');

//Windows Live Writer
remove_action('wp_head', 'wlwmanifest_link');

// WordPress Generator
remove_action('wp_head', 'wp_generator');

// Post Relational Links - Start
remove_action('wp_head', 'start_post_rel_link');

// Post Relational Links - Index
remove_action('wp_head', 'index_rel_link');

// Post Relational Links - Next, Prev
remove_action('wp_head', 'adjacent_posts_rel_link');