The current VyOS container image manipulation delete container image allows force removal of container images - even if they still have a container running.
Drop the --force option from the op-mode script.
This will result in:
[email protected]:~$ delete container image 2636705a815a Error: image used by 6adb0175d47f3c0b07497adafcf174b5273d32a6edc61a7ba4f8ac3fc721599a: image is in use by a container: consider listing external containers and force-removing image