Ubuntu Linux: Delete directory command in Terminal

You need to use the rmdir utility / command. The rmdir utility
removes the directory entry specified by each directory argument,
provided it is empty. Arguments are processed in the order given. In
order to remove both a parent directory and a subdirectory of that
parent, the subdirectory must be specified first so the parent
directory is empty when rmdir tries to remove it.
Remove / Delete directory called /tmp/fooOpen the terminal. Type the following command:
$ rmdir /tmp/foo