Remove All Unwanted Meta, Scripts and Styles (including Emoji) from the WordPress Header.

wp_remove_header_junk.php

// =========================================================================
// REMOVE JUNK FROM WORDPRESS HEAD
// =========================================================================
// REMOVE WORDPRESS HEADER META:
remove_action('wp_head', 'rsd_link'); // remove really simple discovery link
remove_action('wp_head', 'wp_generator'); // remove wordpress version meta tag
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); // remove random post link
remove_action('wp_head', 'parent_post_rel_link', 10); // remove parent post link
remove_action('wp_head', 'adjacent_posts_rel_link', 10); // remove the next and previous post links
remove_action('wp_head', 'adjacent_posts_rel_link_wp_head', 10); // remove the next and previous post links
remove_action('wp_head', 'wp_shortlink_wp_head', 10); // remove wp shortlink 
// REMOVE EMOJIS:
remove_action('wp_head', 'print_emoji_detection_script', 7); // Emoji Scripts and Styles
remove_action('admin_print_scripts', 'print_emoji_detection_script'); // Emoji Scripts and Styles
remove_action('wp_print_styles', 'print_emoji_styles'); // Emoji Scripts and Styles
remove_action('admin_print_styles', 'print_emoji_styles'); // Emoji Scripts and Styles
add_filter('emoji_svg_url', '__return_false'); // Removes the dns-prefetch meta for Emoji (s.w.org)
// REMOVE REST API:
remove_action('wp_head', 'rest_output_link_wp_head', 10); // Remove the REST API lines from the HTML Header (api.w.org)
remove_action('wp_head', 'wp_oembed_add_discovery_links', 10); // Remove the REST API lines from the HTML Header (api.w.org)
remove_action('rest_api_init', 'wp_oembed_register_route'); // Remove the REST API endpoint.
add_filter( 'embed_oembed_discover', '__return_false'); // Turn off oEmbed auto discovery.
remove_filter('oembed_dataparse', 'wp_filter_oembed_result', 10); // Don't filter oEmbed results.
remove_action('wp_head', 'wp_oembed_add_discovery_links'); // Remove oEmbed discovery links.
remove_action('wp_head', 'wp_oembed_add_host_js'); // Remove oEmbed-specific JavaScript from the front-end and back-end.