I think you should familiarize yourself with Docker. you are using terms and technologies like Portainer, container and image without basic understanding.
you don’t need to delete images to kill your system. you can even create brand new account using occ without recreating your system.. but you should read and understand 101: Self-hosting information for beginners and 101: backup what and why (not how) before you continue and upload important data into the new shiny application to avoid data_loss