My first thought, which you might not appreciate, is that you shouldn't be logged in as root if you don't know how to delete a directory!

The delete command is rm (remove), and to delete an entire directory you need to specify the -r switch (ie. rm -r) which will recursivly delete the directory and all files. So, to remove your directory:

Be careful though, as one wrong slip could result in you deleting most of your filesystem (ie. emptying the device of files!)