Удалить:

sudo systemctl stop snapd.service
sudo systemctl disable snapd.service
sudo apt autoremove snapd
sudo dpkg --purge snapd
 
rm -rf ~/snap
sudo rm -rf /snap
sudo rm -rf /var/snap
sudo rm -rf /var/lib/snapd

#!/usr/bin/sh
 
#rm disabled packs
LANG=en_US.UTF-8 snap list --all | awk '/disabled/{print $1, $3}' |
  while read snapname revision; do
    snap remove "$snapname" --revision="$revision" --purge
  done
 
#rm cache
rm /var/lib/snapd/cache/*

sudo ./snappurge.sh

Показать сохранённые snapshot:

sudo snap saved

Удалить (забыть) snapshot с id 21:

 sudo snap forget 21

https://askubuntu.com/questions/1075050/how-to-remove-uninstalled-snaps-from-cache