Deleting/removing files and directories involves moving the cursor to the file/directory to be deleted and pressing "D". Directories must be empty first before they can be successfully removed.
This is not a default I'm happy with, but as with everything else in Vim, netrw is customisable. The default command for deleting local directories is
rmdir which requires the directory to be empty. By setting
g:netrw_localrmdir to something else, such as
rm -r I get the behavior I want.
Excerpt from my .vimrc:
" Allow netrw to remove non-empty local directories " let g:netrw_localrmdir='rm -r'