I’m assuming you want to hide the author page on the site itself (and not in wp-admin).
To do that, just create a new template file called author-{$id}.php, where {$id} is replaced by the ID of the author you want to hide. So if the author ID is 6, the template file should be called author-6.php.
Inside the new file, put this in:
<?php
header( "HTTP/1.1 301 Moved Permanently" );
wp_redirect( get_home_url() );
exit;
?>
Now when you try to load the author’s page, it will just redirect to the site visitor to your home page.
(Source)