Normally all the cpanel servers would have pureftp running by default, you need to change it to proftpd inorder to make it working. You can switch it using the following command
server [~]# /scripts/setupftpserver proftpd
Now we need to create a new ftp user with the required home directory. You can use the following command to create a ftp user email@example.com
server [~]# /usr/local/cpanel/bin/proftpd_passwd cpanelusername -a
server [~]# /usr/local/cpanel/bin/ftpupdate
To delete an ftp accounts, run the command.