linux mint - Root user can't remove folder

There is a folder /mnt/shared which root user can't access/modify or remove.

# ls -lai /mnt
total 4
16662 drwxr-xr-x  3 root root    0 Mar 27 14:30 .
    2 drwxr-xr-x 23 root root 4096 Mar 27 14:26 ..
16663 dr-xr-xr-x  2 root root    0 Mar 27 14:30 shared
# chattr -i /mnt/shared/
chattr: No such file or directory while trying to stat /mnt/shared/
# rmdir /mnt/shared/
rmdir: failed to remove ‘/mnt/shared/’: Permission denied
# cd /mnt/shared/
-su: cd: /mnt/shared/: No such file or directory
# ls -i /mnt
16663 shared
# find . -inum 16663 -delete
find: `./shared': No such file or directory

Running fsck doesn't help.
OS: Linux Mint 17.3

Answer

Finally i found what caused an issue - autofs.
After stopping autofs service undeleteable folder disappeared.

#service autofs stop