How to force 'docker login' command to ignore existing credentials helper?

Logging out the current user, before logging in with a different user name worked for me. Logging out removed the saved docker credentials.

docker logout <reponame> 
docker login <reponame> 

Unfortunately, Docker (as of 18.06) first looks for the docker-credential-* binaries, and if it finds any of them, it will automatically overwrite the "credsStore" value in ~/.docker/config.json.

Your only workaround would be to install docker-credential-pass in your home directory so that Docker will use that instead of docker-credential-secretservice. docker-credential-pass does not require a GUI.

Steps to install docker-credential-pass:

docker login fails on a server with no X11 installed

To avoid using a credsStore and to store a plaintext auth token in your docker config (e.g. ~/.docker/config.json), delete the "credsStore" key from your docker config file and rerun docker login.

When you run docker login, it will give a warning but will save the auth token into the file.

$ docker login
Username: someuser
Password:
WARNING! Your password will be stored unencrypted in ~/.docker/config.json.
Configure a credential helper to remove this warning. See
https://docs.docker.com/engine/reference/commandline/login/#credentials-store

Login Succeeded

The resulting docker config file should look like this:

{
        "auths": {
                "your.docker.registry": {
                        "auth": "dXNlcm5hbWU6cGFzc3dvcmQK="
                }
        }
}

The auth token is simply a base64 encoded string of the form username:password.

This worked for Docker Engine versions 19 and 20.