Trim last commit

By accident, I pushed a commit with a real email address which should be kept private. It is the last, email-identified commit (b57e38833a25eca8f9dfa531f96aa9bdd495cc8c) of the repo. I’ve tried force push after deleting releases, switching branches and all sorts of things, but no avail, since it had a published release 🙁
I need the email address to be the provided, private email and user. Sorry for the inconvenience due to my mistake.