I used root user for ubuntu extract a folder.But I can't delete them now.Can
you help me?
My guess is that you are trying to delete them with a normal user, but you extracted them with root causing you not to have the proper permissions. Which case, go in as root and delete it.
Other than that we really can't help unless this happens to be a bug with the what ever command you are deleting them with. (Presumably, "rm -d" or "rmdir".) This is a mailing list for the Coreutils. You might be better served by asking at http://ubuntuforums.org/. I could be wrong, though. More context would be needed to see if this really is a bug.