I recently had to reset the owner account on my Home Assistant instance after forgetting the password.

Thankfully Home Assistant provides comprehensive documentation that walks through several recovery options.

The notes below capture the exact flow I used on a Home Assistant OS install, where the supervisor runs Home Assistant inside a managed container.

Following the container command line documentation, the steps I needed were fairly similar: first SSH to the device (via the SSH add-on).

Once connected, get a shell in the Home Assistant container to call hass:

docker exec -it homeassistant bash

Then reset the password:

hass --script auth --config /config change_password <username> <new-password>

Finally, log back to the host by calling exit and then restart Home Assistant:

ha core restart

Verify by signing in to the UI with the updated password to confirm the change.