Step 1: Add the node to the system-config.yaml.
Steps for replacing a CPU node:
Step 1: Put the node in Maintenance mode
Documented in the section about putting a node in Maintenance mode
Make sure to select the Move All Virtual Machines option:
Wait until the node is in Maintenance mode and that all virtual machines have moved to another node
Step 2: Shutdown the node
Step 3: Put the node in Decommission mode, documented here
Step 4: Remove the node from system-config.yaml.