Plesk 11.x / Linux :: How To Stop Creating FTP Accounts And Remove Existing Ones

I have noticed that for each new subscription I create Plesk automatically creates an FTP account. Further; I cannot delete this. (It seems the Remove button would allow me to delete additional FTP accounts but not the one added when the subscription was created).

I would like:

1) To delete these system created FTP accounts

2) To prevent it doing this in future. I would like to create subscriptions without FTP accounts.

I'd prefer to do it this way and leave the FTP server running. However; I am wondering about disabling FTP access altogether if I have to. I do use SFTP. I'm afraid my Linux knowledge is so limited I don't know if SFTP uses the FTP server; so if I turned off the ftp server whether that would prevent sftp access?

The motivation for doing this is that while I have 'customers' and subscribers in fact I am the only user and will transfer files to the server by SFTP and then move them around the server logged on via SSH. Since I'm not using FTP it seems sensible not to have all these accounts floating about.