(loose ref: https://www.mail-archive.com/help-guix@gnu.org/msg10948.html)
sudo systemctl disable guix-daemon.service
sudo systemctl disable gnu-store.mount
systemctl reboot
sudo rm -rf /gnu
sudo rm -rf /var/guix
sudo rm -rf /var/log/guix
sudo rm /usr/local/bin/guix
sudo rm -rf /usr/local/share/info/guix*
sudo rm /etc/systemd/system/guix-daemon.service
sudo rm /etc/systemd/system/gnu-store.mount
sudo rm /etc/profile.d/guix.sh
sudo rm -rf /etc/guix
sudo rm /etc/bash_completion.d/guix
sudo rm /etc/bash_completion.d/guix-daemon
(log out, log in)
rm ~/.guix-profile
rm -rf ~/.cache/guix
rm -rf ~/.config/guix
for i in $(seq -w 01 10); do sudo deluser guixbuilder$i; done
sudo delgroup guixbuild