Remove Yoast SEO version from header

functions.php

add_action('get_header', 'start_ob');
add_action('wp_head', 'end_ob', 999);

function start_ob() {
	ob_start('remove_yoast');
}
function end_ob() {
	ob_end_flush();
}

function remove_yoast($output) {

	if (defined('WPSEO_VERSION')) {

		$targets = array(
			'<!-- This site is optimized with the Yoast WordPress SEO plugin v'.WPSEO_VERSION.' - https://yoast.com/wordpress/plugins/seo/ -->',
			'<!-- / Yoast WordPress SEO plugin. -->',
			'<!-- This site uses the Google Analytics by Yoast plugin v'.GAWP_VERSION.' - https://yoast.com/wordpress/plugins/google-analytics/ -->',
			'<!-- / Google Analytics by Yoast -->'
		);
		
		$output = str_ireplace($targets, '', $output);
		$output = trim($output); 
		$output = preg_replace('/^[ \t]*[\r\n]+/m', '', $output);
	}
	return $output;
}

Or...just use another plugin :)

We’ve Migrated from Yoast SEO - https://roots.io/weve-migrated-from-yoast-seo/

Hello,
How to remove this line from inspect element.