What platform? Without this, I am just giving some general advice.
This is easy to achieve and I have just made something similar for my company but it depends on a number of things and will usually require a bit of scripting.
The easiest way is to find a FTP server that supports a database for user membership, then all you need to do is create a small website in the language of your choice and simply take username and password along with anything else you want. You can then set that script to send you a email with all the details or simply have it display on another (admin) webpage, and a delete or confirm button.
When you press delete, it deletes the entry (of course!) and when you click confirm, it can enter the details in to the database of the FTP server.
You can also use a FTP server that has membership in any form (such as XML files or windows / unix accounts) but having one that has a database backend is so much simpler.
Also, You could have all users in one database, if they are confirmed or not, but I said the above just for simplicity as you probably do not want thousands of unconfirmed / disabled ftp users.