Github offers convenient webspace related to users as well as to organization (although they are access differently):

  • Users can access their webspace by creating a repository called user.github.com. Everything in this folder is accessible over the url https://user.github.com .
  • Webpages related to projects are in need of a branch of the related repository called gh-pages. The website is then accessible over https://user.github.com/repoOfProject

When removing a repository, the related webpages are not automatically removed from the users/organization website. It is needed to update the users/organization websites manually to trigger the changes on the webserver of github.