Hide/Disable Yoast SEO's nagging display features in the WordPress backend

functions.php

<?php
/**
 * Disable Yoast SEO's darn admin bar icon
 */

function yoast_hide_admin_bar() {
	
	global $wp_admin_bar;
	$wp_admin_bar->remove_menu('wpseo-menu');
}

add_action( 'wp_before_admin_bar_render', 'yoast_hide_admin_bar' );

/**
 * Hide Yoast SEO's publish box icons
 */

function yoast_hide_publish_box_icons() {
	
	echo '<style type="text/css">
		
			.yoast-seo-score {
				display: none !important;
			}
			
		</style>';
}

add_action('admin_head', 'yoast_hide_publish_box_icons');