Let's Control It

If I want to erase the NodeMCU totally - how can I do that. It seems like the settings is still there after a new upload

Usually erasing the part in ESP memory where the settings are stored is enough.

To do that connect a short between the RX and the TX pin, repower or reset the ESP. Wait a while (minute or so) to let the erase process finish.
Disconnect and reconnect power and your old settings should be cleared.

Thanks I will test that

I did as you said but the nodemcu seems dead
if I connect it to the pc it does not see it and I can not flash

That is really weird. I have used this method several times when something gets stuck. Never had any problem.