Managing access to your personal repositories
You can give people collaborator access to repositories owned by your personal account.
If you're using GitHub Free, you can add unlimited collaborators on public and private repositories.
Inviting collaborators to a personal repository→
You can add users as collaborators to your personal repository.
Removing a collaborator from a personal repository→
When you remove a collaborator from your project, they lose read/write access to your repository. If the repository is private and the person has created a fork, then that fork is also deleted.
Removing yourself from a collaborator's repository→
If you no longer want to be a collaborator on someone else's repository, you can remove yourself.