# deletes the branch if it has already been fully merged in its upstream branch
$ git branch -d <branch_name>
# The -D option is an alias for --delete --force, which deletes the branch "irrespective of its merged status." [Source: man git-branch]
$ git branch -D <branch_name>
# Delete Remote Branch
# In most cases, <remote_name> will be origin
$ git push <remote_name> --delete <branch_name>