rm -r directory

or

rm -rf directory

an explanation can easily be retrieved with man rm, here is an extract:

-r, -R, --recursive
          remove directories and their contents recursively
-f, --force
          ignore nonexistent files and arguments, never prompt 

also from man rmdir:

rmdir

Remove directory, this command will only work if the folders are empty.

use sudo before command if it displays permissions denied.