Hello Photoed,
This question can mean a few different things. I will try to answer as many as I can.
If you are looking to give FTP access to someone you can check here:
Creating an FTP account in Cpanel. You can set their root folder here limiting their access or even giving them full access.
If you are looking to limit the amount of data bandwidth an FTP account can use, you can set that in the same area as you created the account in. Using the link above you see you can set that as part of their account, limiting them with the Quota option.
If you are looking to limit the user to specific permissions within the files they have access to, any user logged into FTP has full permissions to all folders and files under their control. They have access to all folders and files underneath their root folder.
I hope this answers your question. If you have any more questions or comments on the issue please leave a comment below so we can assist you further.
Thank you,
Scott M