Creating Sub Domain FTP Account in cPanel
a) "Login" is exactly as your sub domain name.(Example: If your sub domain is support.exabytes.com, enter "support" as login.)
b) Enter Password.
c) Directory is your sub domain directory. (Example: /home/exabytes/public_html/support/ )
If you enter a single / in the directory box, the new FTP user will have access to the entire public_html directory and all directories under it. If you just want the new user to be able to access a sub-domain, just set the directory box to the same value as the sub-domain's root name, which is listed in parenthesis on the sub-domain section of this control panel.
Please be aware that the new user will have read/write access to the directory you choose and every directory below it. For example, if you choose to add the user john, and give the user access to /home/exabytes/public_html/john directory, the user will be able to add, edit, rename and remove any file or directory in /home/exabytes/public_html/john.