You are attempting to delete the last defined rank, but one or more SCSI host ports are attached to the rank. You must delete all objects that are logically configured on the rank (including volumes, logical control units, volume groups and host ports) before you can delete this rank. You do not need to delete arrays, and you do not need to delete the default volume groups 10, 20 and 30.
Ensure that no other objects are logically configured on the rank, and then resubmit the task.