Remove the trailing slash from the canonical meta link form Yoast SEO

canonical_remove_trailing_slash.php

<?php

/* Place in functions.php */
function prefix_filter_canonical_example( $canonical ) {
	if ( substr( $canonical, -1 ) == "/" ) {
		return substr($canonical, 0, -1);
	}
	return $canonical;
}
add_filter( 'wpseo_canonical', 'prefix_filter_canonical_example' );