Restrict server from FTP and SSH

How can I restrict a server owner from FTP or SSH access?
On the Edit Virtual Server > Edit FTP Users there’s the default user created with the new server that has access to FTP and SSH, but its checkbox can’t be check and so the user can’t be deleted.
Also, on the Server Owner Limits page there’s the drop-sown option for Allowed login type but it contains only one field, which is: Email, FTP and SSH.