After 3 painful days of playing whack-a-mole trying to change my passwords and reprogram all my devices to use them, I think it is impossible without some serious skills. I did not even get around to trying to change my NodeRed password, lol, so many wasted hours and so much pain (SSH, MQTT, HA, ESPhome, Google Assistant Voice, Tasmota…). In the end I am not sure it is even possible to change the passwords and get my home working again. I think it would require starting over totally, with a secure password.
Here is the way to disable the notifications according to a moderator here: