Codex will be back soon. There was a combination of a database issue and it was being crawled to the point where it was killing the server that it was on (this one).
It is because you’re running it under mod_php, which reads and writes as the web server’s user:group (in your case httpd:httpd), so files uploaded via mod_php can’t be deleted by FTP or SFTP unless you have superuser privs.
But just use php to delete the files either directly or with a php-based file manager.
