Do you want a clean Home Assistant install or a clean RPi OS install? You can achieve a clean HA install fairly easily without completely nuking everything.
But even before that, the very first thing you should do so can feel comfortable with the process, is to create a good backup of the whole card/disk. That way you can just write the original image back if anything goes south..
Then you can just move the Home Assistant venv folder and Home Assistant config directories, then follow the venv install process as though it were a new install. If you followed this guide:
then the venv is located at
/srv/homeassistant
and the config directory would be
/home/homeassistant/.homeassistant
So you could just move the old directories out of the way:
sudo mv /srv/homeassistant /srv/homeassistant-old
sudo mv /home/homeassistant/.homeassistant /home/homeassistant/.homeassistant-old
Another big note, as I mentioned, my install has a custom python3.8 package a community member built:
It’s important if you installed Home Assistant on Raspbian Buster before ~Dec. 2020, because you’d probably be running 3.7, which Home Assistant no longer supports.