Once a port has been assigned to a Dynamic POD license port set, it remains licensed (or "reserved") until you remove the port from the port set. You remove a port from the port set by releasing the port with the dpod release command. Releasing a port removes it from the Dynamic POD license port set; the port appears as unassigned until it comes back online.
To prevent a port from coming back online and taking a POD assignment, disable the port and save the running configuration. This action will disable the port persistently.
A port POD assignment can only be released if the port is currently offline. Use the shutdown command to disable the port or use the chassis disable command to disable the switch if you plan to release multiple ports.