How do I disable Git Credential Manager for Windows?

OK, I discovered that you need to either avoid checking the "Git Credential Manager" checkbox during the Git for Windows installer, or (after installation) run the Bash shell as Administrator and use git config --edit --system to remove the helper = manager line so that it is no longer registered as a credential helper.

For bonus points, use git config --edit --global and insert:

[core]
    askpass =

To disable the OpenSSH credentials popup too.

I was able to uninstall the Git Credential Manager for Windows using the uninstall option:

git-credential-manager.exe uninstall

Run this command in C:\Program Files\Git\mingw64\libexec\git-core