過去の秘密の消去にはbfgっていうツールを使うのがいいのかな？
Removing sensitive data from a repository - GitHub Docs https://docs.github.com/en/github/authenticating-to-github/removing-sensitive-data-from-a-repository
docs.github.comRemoving sensitive data from a repository - GitHub DocsIf you commit sensitive data, such as a password or SSH key into a Git repository, you can remove it from the history. To entirely remove unwanted files from a repository's history you can use either the git filter-branch command or the BFG Repo-Cleaner open source tool.