Forgot to add a user to local user accounts before running Sysprep-generelize with Unattend XML file on Win10 pro machine

Question

I forgot to add a user to the local user accounts before running Sysprep-generelize with Unattended XML file on Win10 pro machine an I'm locked out The Admin user became unavailable and there are no users in the system. Is there a way to add a user "outside" the image? What else is possible before reformatting the image ?