I am not sure what the original poster meant, removing iSCSI from storage configuration file will cause the iSCSI not to be disovered/logged into on next reboot.
Perhaps the idea was that you can remove the iSCSI configuration, but then you need to manually manage that aspect via "iscsiadm" on your own. In that case PVE will not be aware of the iSCSI, it will only manage the LVM part.