The most obscure commands of git (unless you know the internals) is the one to remove remote branches. You have to do a push with the branch name lead by a colon:
git push origin :branch
Actually it is not that obscure, it's more like
"git push origin <nothing>:branch".
But it tends to be not that obvious in the beginning ;)
What about git push --delete remote-name branch-name? Not that obscure even if you don't know the internals.
git push --delete remote-name branch-name