In case you are still having problems, I want to understand exactly what your problem is.
1. The subject indicates trouble deleting ftp accounts. You give two links, and indicate that you did succeed in deleting the account using the second link. My observation was that I got the same result regardless of which link I used, but I did not actually try to delete an account. There may be a browser-dependent or cookie-related bug causing the first link to fail for you. In either case, you were able to delete, it appears.
2. The more important issue seems to be setting up the correct file access options. The only choice I see, when creating an ftp account, is where the root gets placed. There is only one set of "folder permissions" for your entire account, to the best of my knowledge. Presumably the ftp account can change any folder visible to it, under the same conditions as the main account can. The ftp account is controlled by making only certain folders visible to it, usually a sub-folder with the name of the ftp account. With proper settings, you can allow or prohibit creation of new folders under that folder.
You normally would return to the file management page to change the default permissions. You can create the ftp root folder there, change permissions and/or owner of the ftp root folder, and create sub-folders if desired.
If I have not understood your problem and you still have one, please clarify what else is failing or exactly what you need to do.