Switch off the branch that you want to delete. Most of the time, switching to master will allow you to delete a working branch: :
$ git checkout master
$ git branch -D mybranch
Delete the remote branch off GitHub: :
$ git push origin --delete mybranch
Enter passphrase for key '/home/vhu/.ssh/github/id_rsa':
To git@github.com:whowutwut/xcat-doc.git
- [deleted] mybranch
Verify branch is gone: :
$ git branch -r
origin/HEAD -> origin/master
origin/large_cluster
origin/master
origin/sync
upstream/master
There are times when you delete the branch off your local machine or from GitHub and it's become out of sync, you sync up the list, run the following: :
git remote prune origin