We are quick to make a new site. These collect. Here are some commands handy for removing them.
First find what is on the server.
ssh fed.wiki.org 'du -s .wiki/*' | sort -nr | pbcopy
Then use a text editor to trim this to a list of sites to go.
pbpaste | ssh fed.wiki.org \ 'while read n i; do echo $i; rm -rf $i; done'