Final answer:
To remove a service from a swarm cluster, the correct command is 'docker service remove'. It's used to permanently delete a service from the Docker swarm environment.
Step-by-step explanation:
The command to remove a service from your swarm cluster is A) docker service remove. This command is used when you want to permanently remove a service from your Docker swarm.
For example, if you have a service called 'my-service', you would use the command docker service rm my-service to remove it from the swarm.