functions.php

/* "wp" is the earliest possible hook before rendering a page */
add_action( 'wp', 'disable_author_page' );

function disable_author_page() {

	/* get global $wp_query object */
	global $wp_query;

	/* If an author page is requested, answer with 404 
	
	if ( $wp_query->is_author ) {

		$wp_query->set_404();
		status_header( 404 );
		get_template_part( 404 );
		exit();

	}
	*/
	
	/* If an author page is requested, redirect with 301 */
	if ( $wp_query->is_author ) {

		wp_safe_redirect( get_bloginfo( 'url' ), 301 );
		exit;
	}

}