if you change the permissions of that file to say root.root then I dont' think the users would be able to overwrite or delete the file using FTP client. I think this could also be an alternative solution as well
Thanks, I guess that the easiest solution is to create a root file, but I want that this file (with the root access only) would be created automatically when I open a new account (Like the default DirectAdmin page), Is there any way to do it?