With the host registration management workflows, you can add a host to a cluster, disconnect or reconnect a host from a cluster, and others.

Add host to cluster
Adds a host to the cluster. This workflow fails if it cannot authenticate the SSL certificate of the host.
Add standalone host
Registers a host as a standalone host.
Disconnect host
Disconnects a host from vCenter Server.
Reconnect host
Reconnects a disconnected host by providing only the host information.
Reconnect host with all information
Reconnects a disconnected host by providing all information about the host.
Remove host
Removes a host and unregisters it from vCenter Server. If the host is part of a cluster, you must put it in maintenance mode before attempting to remove it.