functions.php

/**
 * Remove the "nofollow" attribute from all comments author's links
 * except for a specific author.
 */
function dofollow_blog_author_comment( $return, $author ) {
		if ( $author === 'Your Name' ) {
				$return = str_replace( "rel='external nofollow ugc'", '', $return );
	 	}

		return $return;
}
add_filter( 'get_comment_author_link', 'dofollow_blog_author_comment', 10, 2 );