The easiest way to disable a specific group of accounts, such as the root user and those with sudo privileges, from accessing an FTP server is to use a PAM list file as described in Section 4.4.2.4, “Disabling Root Using PAM”. The PAM configuration file for vsftpd is /etc/pam.d/vsftpd.

It is also possible to disable user accounts within each service directly.

To disable specific user accounts in vsftpd, add the username to /etc/vsftpd.ftpusers.