To disable access to author page (author archive), simply add this code snippet to functions.php file:

// Disalbe access to author page
add_action('template_redirect', 'my_custom_disable_author_page');

function my_custom_disable_author_page() {
	global $wp_query;

	if ( is_author() ) {
		$wp_query->set_404();
		status_header(404);
		// Redirect to homepage
		// wp_redirect(get_option('home'));
	}
}
add_action( 'template_redirect', 'remove_author_pages_page' );