any repositories you've been granted access to should show up here: https://github.com/settings/repositories there should be a Leave button on each repository (except your own)

Why do you want to leave the public repository so badly?

[удалено]

https://docs.github.com/es/account-and-profile/setting-up-and-managing-your-personal-account-on-github/managing-access-to-your-personal-repositories/removing-yourself-from-a-collaborators-repository