Why am I unable to delete a volume on a target node?

You cannot delete a volume on a target node that has an active iSCSI connection. Target nodes with an active iSCSI connection have a plus sign in front of their name (the name is prefaced with naa followed by a string of numbers and letters). If the volume you want to delete has an iSCSI connection, log out of the target node and then delete the volume on that target node.