If you’ve never run Xibo in the containers before, then you’d simply create config.env, edit it to add a MySQL password, and then run docker-compose up -d
If you have run them before, and you no longer need the contents of that CMS, then run:
docker-compose down
sudo rm -r /usr/lib/docker/xibo-docker/shared/db
docker-compose up -d
That will delete the existing database instance, and then create a fresh one, importing your import.sql and then running the upgrade on it.