From EZP Knowledge Base

With cPanel, you can view who is currently connected via FTP to your account. You can also terminate any of these active FTP sessions. While this is kind of neat and appeals to micromanaging god mode part of me, from a security standpoint if someone is accessing your account via FTP without your authorisation, terminating their FTP session really isn't going to do much as they likely have access to a lot more then just FTP. However, it can be done, so we will tell you how to do it!

Follow these steps to monitor and terminate connections:

• Login to cPanel.
• Click the FTP Session Control icon.

• You will see a list of all the active FTP sessions.
• You will notice a "disconnect" link next to each session, if you wish to terminate one you just have to click it.