Updating a workload domain is a multi-step process. Perform the steps in the order in which they are documented.
When you delete a workload domain, it is recommended that you decommission the host, image it with the current, upgrade ESXi version, and then perform the add host procedure. This ensures that when the hosts are required for new workload domain, they are ready and their ESXi versions up to date. (When a workload domain is deleted, the hosts revert to the ESXi version their rack was originally imaged with.)