Here are two simple filters to remove the rewrite of <title> content functionality provided by WordPress SEO:
// Remove the wp_title filter
add_action( 'init', 'remove_wpseo_title_rewrite' );
function remove_wpseo_title_rewrite() {
        global $wpseo_front;
	remove_filter( 'wp_title', array( $wpseo_front, 'title' ), 15 );
}
// Remove the title metabox from backend UI
add_filter( 'init', 'remove_wpseo_title_rewrite_metabox' );
function remove_wpseo_title_rewrite_metabox( $metaboxes ) {
	if ( isset( $metaboxes['title'] ) )
		unset( $metaboxes['title'] );
	return $metaboxes;
}