When I perform branch -a:
branch -a
$ git branch -a * master remotes/origin/HEAD -> origin/master remotes/origin/hello remotes/origin/master
You need to remove it from the remote with the following command:
git push origin --delete hello
When you are running git branch -rd origin/hello you are deleting your local branch only. The code above removes it from the origin repo.
git branch -rd origin/hello