When you remove an ESXi host from a Trusted Cluster or Trust Authority cluster, the host continues to retain its vSphere Trust Authority configuration. The alarm notifies that the moved out host must be decommissioned by following a specific procedure. This is a necessary step the user must perform in order to remove the existing vSphere Trust Authority configuration if they desire to continue using the host. Failing to perform the decommission procedure results in a security risk and undefined behavior if the user decides to use the host in other Trusted Infrastructure clusters. Decommissioning a host removes its vSphere Trust Authority Configuration.