git push -d <remote_name> <branchname>
git branch -d <branchname>

Note: In most cases, <remote_name> will be origin.

Delete Local Branch

To delete the local branch use one of the following:

git branch -d <branch_name>
git branch -D <branch_name>

• The -d option is an alias for --delete, which only deletes the branch if it has already been fully merged in its upstream branch.
• The -D option is an alias for --delete --force, which deletes the branch “irrespective of its merged status.” [Source: man git-branch]
• As of Git v2.3, git branch -d (delete) learned to honor the -f (force) flag.
• You will receive an error if you try to delete the currently selected branch.

Delete Remote Branch

As of Git v1.7.0, you can delete a remote branch using

$ git push <remote_name> --delete <branch_name>

which might be easier to remember that

$ git push <remote_name> :<branch_name>

which was added in Git v1.5.0 “to delete a remote branch or a tag.”

Starting with Git v2.8.0, you can also use git push with the -d option as an alias for --delete. Therefore, the version of Git you have installed will dictate whether you need to use the easier or harder syntax.