I saw a lot of big projects/repositories with hundreds or even thousands of stale branches where nothing really happens. Usually, no one cares to clean up all this mess. There is a nice simple GitHub tweak where you can prevent this.
Github branches can be automatically deleted after press on the merge button.
You need to be a repository admin:
- Navigate to repository "Settings"
- Scroll down to the "Merge button" section
- Activate "Automatically delete head branches" checkbox
If you're merged something accidentally and want your branch back? Don't worry, you'll be able to restore deleted branches.