To remove itself from a cluster, a Broker must formally "leave" the cluster. When a Broker leaves a cluster, it informs its peers (at least one of them) about leaving. When the last Broker leaves a cluster, that cluster ceases to exist.

Unless it is the only remaining Broker in a cluster, it is important that at least one of the Broker's peers be running when you remove a Broker from a cluster. Otherwise, the state of the cluster will be inconsistent.