Cannot delete folder on Synology NAS?

I logged in as root and tried to recursively delete the folder /volume2/Name using rm -rf It started and deleted all the files/directories inside this folder Name, but it cannot remove the folder itself even though I am root: rm: cannot remove 'Name’: Operation not permitted The command ls -l list the permissions for this folder as: d---------+ 1 root root Synology has a special tool called synoacltool for these ACL permissions, but I don't know to use it. So what do I need to do in order to be able to remove this (empty) folder?