PHP// Disable REST API link tag
remove_action('wp_head', 'rest_output_link_wp_head', 10);

// Disable oEmbed Discovery Links
remove_action('wp_head', 'wp_oembed_add_discovery_links', 10);

// Disable REST API link in HTTP headers
remove_action('template_redirect', 'rest_output_link_header', 11, 0);