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.
Setting the default branch
The default branch is considered the base branch in your repository, against which all pull requests and code commits are automatically made, unless you specify a different branch.
Viewing branches in your repository
Branches are central to collaboration on GitHub, and the best way to view them is the branches page.
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.