I've created a user called "ftp-acc" and limited it to a single directory using VSFTPD. When I login to the account in Filezilla using FTP, it is successfully restricted to a single directory.
However, when logging in with the same credentials using SFTP, the user can access other directories as well.
How can I disable SFTP for the user "ftp-acc"?
First point , FTP and SFTP both are different. FTP normal file transfer protocol but SFTP is secure file transfer protocol and this service is from SSH not a stand alone service.
If you want to disable SFTP for one user then open sshd_config file in server(machine you are trying to access) and
DenyUsers ftp-acc and then restart sshd service with
service sshd restart
