WordPress SEO by Yoast filters

wp-seo-filters.php

<?php

// Remove Canonical Link Added By Yoast WordPress SEO Plugin
function at_remove_dup_canonical_link() {
	return false;
}
add_filter( 'wpseo_canonical', 'at_remove_dup_canonical_link' );


function wpseo_attachment_canonical_parent( $canonical ) {
	if ( is_attachment() ) {
		global $post;
		$attachment = get_post( $post->ID );
		$parent_post_id = $attachment->post_parent;
		$canonical = get_permalink( $parent_post_id );
	}
	return $canonical;
}
add_filter( 'wpseo_canonical', 'wpseo_attachment_canonical_parent' );


function wpseo_canonical_exclude( $canonical ) {
	global $post;
	if ( $post->ID == 4350) {
		$canonical = false;
	}
	return $canonical;
}
add_filter( 'wpseo_canonical', 'wpseo_canonical_exclude' );