Managing branches in your repository
Whenever you propose a change in Git, you create a new branch. Branch management is an important part of the Git workflow. After some time, your list of branches may grow, so it's a good idea to delete merged or stale branches.
Viewing branches in your repository→
Branches are central to collaboration on GitHub, and the best way to view them is the branches page.
Changing the default branch→
If you have more than one branch in your repository, you can configure any branch as the default branch.
Deleting and restoring branches in a pull request→
If you have write access in a repository, you can delete branches that are associated with closed or merged pull requests. You cannot delete branches that are associated with open pull requests.