So you can remove the author-pages with an author.php file in your (child) theme, but what if you don’t want to touch the theme you ask? Well, I just added this code snippet to two of the sites I manage to stop user-enumeration (which can be done on any WordPress site by going to /index.php?author=1):
add_action('wp','no_author_page'); function no_author_page() { if (is_author()) { global $wp_query; $wp_query->set_404(); status_header( 404 ); get_template_part( 404 ); exit(); } }
Disclaimer: the bulk of above code was shamelessly copy/ pasted from https://wordpress.stackexchange.com/a/27124