The message “Directory Not Empty” actually contradicts the file list shown on the server. In FileZilla it seems as if the directory is empty, but in reality there are some hidden files/folders present in that directory – which FileZilla won’t show by default.
The directory will probably look like this. It seems as if no other files are present.
By changing some settings within FileZilla, you can show those hidden files, after which deleting the non-empty folder will succeed.
Go to “Edit” and proceed to “Options”.
In the following dialogue window, go to the menu-item “Remote file list” and check the option “Always show hidden files“, at the bottom of the window.
When you now restart FileZilla, and reconnect to the FTP server, you will see a hidden file named “.htaccess“.
Now when you try to delete the folder, the file automatically be deleted as well, causing the message “Directory Not Empty” to no longer be shown.