If you no longer want to be a collaborator on someone else's repository, you can remove yourself.

  1. In the upper-right corner of any page, click your profile photo, then click Settings. Settings icon in the user bar
  2. In the left sidebar, click Repositories. Repositories tab
  3. Next to the repository you want to leave, click Leave. Leave button
  4. Read the warning carefully and then click "I understand, leave this repository" Dialog box warning you to leave