During the days when the outlook password prompt gave a real problem, I used to use an inbuilt windows utility/service and remove passwords for outlook, but now I forget the name, this was real good at resolving that problem and it used to work from the CMD or powershell.(Ah... I can't even make up which one it was)
It is not the credential manager, no I did not use the credential manager from the cmd, this was something really at the core of the windows that used to store those outlook and windows passwords and we used to clear them from there, I was using windows 10 all the time when we used this. For the life of me, I just can't remember how I used to call it from cmd. I need to know because I recently came across this issue again and it took me a while to resolve it, but I am confident if I knew the name of the utility that thing would have resolved in 15 minutes rather than in 2 hours as I had to follow all different steps to get to it.