I’m having the same problem as well. I created an account and tried to delete it from the site itself via the profile page. I get an error message instead
Fatal error: Cannot redeclare add_user() (previously declared in /home/***/public_html/pikipoky.com/wp-admin/includes/user.php:17) in /home/***/public_html/pikipoky.com/wp-admin/includes/user.php on line 18
I had a friend create an account and he couldn’t delete his account and got the same fatal error message.