Any of the following will work:
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Just transfer ownership of the repo to another user and have them add you as a collaborator.
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If someone forks your repo, then you delete the original, their fork is still there, unless it’s a private repository. they can then add you as a collaborator on their fork repo.
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Another user can simply clone your repo (commits intact), create a new repo on GitHub, add the new repo’s remote info, and push your repo up to their new one. (Then, they can add you as a collaborator.)