We can delete pages from the Dot Wiki files even though the wiki server itself won't (yet) do this.
Other users may have links to a page that will fail without explanation when deleted. Consider simply replacing the page with a pointer to a preferable page.
Login and change directory to the desired site's pages subdirectory.
cd .wiki/foo.bar.wiki.org/pages
Check that the page in question is in fact not wanted.
less bad-page
Remove the page and coax wiki to rebuild the sitemap without it.
rm bad-page rm ../state/sitemap.json