Can't remove directory

I’m attempting to remove a folder (a LXC container that wasn’t created correctly) from the drive attached attached to /srv.

root@turris:/srv/lxc# rm -Rf unbuntu_disco
rm: can't remove 'unbuntu_disco/rootfs': Operation not permitted
rm: can't remove 'unbuntu_disco': Directory not empty

How do I remove it?

lxc-info --name unbuntu_disco? maybe it’s running?
mount? maybe the drive is mounted RO?

cd /srv/lxc && lxc-stop -k --name unbuntu_disco && sync && rm -Rv unbuntu_disco

if not then remount the drive with mount -o remount,rw /dev/yourdrive1
and try again to remove.

It’s not running.

rm -Rv unbuntu_disco results in the same error.

Other suggestions?

@craibuc post the output of:
ls -la /srv/lxc/unbuntu_disco
//permissions and ownership check

I guess it’s opened by some proccess. I mean the rootfs folder.
Check what uses that folder with:
lsof +D /srv/lxc/unbuntu_disco/rootfs
//attencion very slow command
and if nothing then check:
lsof +D /srv/lxc/unbuntu_disco
//still slow

permission and ownership:

root@turris:~# ls -la /srv/lxc/unbuntu_disco
drwxrwx-w-    1 root     root            12 Oct 15 19:59 .
drwxr-xr-x    1 root     root            54 Oct 16 06:53 ..
drwxr-xr-x    1 root     root             0 Oct 15 19:59 rootfs

Uses of folder:

# lsof +D /srv/lxc/unbuntu_disco/rootfs
no output


# lsof +D /srv/lxc/unbuntu_disco
no output