Place this code in your theme functions.php

remove_action( 'wp_head', 'print_emoji_detection_script', 7 );
remove_action( 'wp_print_styles', 'print_emoji_styles' );
remove_action( 'wp_head', 'feed_links_extra', 3 );
remove_action( 'wp_head', 'feed_links', 2 ); 
remove_action( 'wp_head', 'rsd_link' );
remove_action( 'wp_head', 'wlwmanifest_link' );
remove_action( 'wp_head', 'index_rel_link' );
remove_action( 'wp_head', 'parent_post_rel_link', 10, 0 ); 
remove_action( 'wp_head', 'start_post_rel_link', 10, 0 ); 
remove_action( 'wp_head', 'adjacent_posts_rel_link', 10, 0 ); 
remove_action( 'wp_head', 'wp_shortlink_wp_head', 10, 0);
remove_action('wp_head', 'wp_generator');
function wpt_remove_version() {  
   return '';  
}  
add_filter('the_generator', 'wpt_remove_version');
function twentyten_remove_recent_comments_style() {  
        global $wp_widget_factory;  
        remove_action( 'wp_head', array( $wp_widget_factory->widgets['WP_Widget_Recent_Comments'], 'recent_comments_style' ) );  
    }  
add_action( 'widgets_init', 'twentyten_remove_recent_comments_style' );