I have lots of old Drupal sites I don't use anymore and am trying to get rid of them all. They're set up as subdomains created in cPanel, so for instance public_html/site1 and public_html/site2 etc. Via FTP I can delete all the contents of these directories except for the /sites directory and all the subfolders and files inside it, where I get "permission denied". Trying to change the file permissions on /sites and its subfolders doesn't work. Can I delete these directories through cPanel somewhere?