func (c *ComputeUtil) deleteDisk() error {
	disk, _ := c.disk()
	if disk == nil {
		return nil
	}

	log.Infof("Deleting disk.")
	op, err := c.service.Disks.Delete(c.project, c.zone, c.diskName()).Do()
	if err != nil {
		return err
	}

	log.Infof("Waiting for disk to delete.")
	return c.waitForRegionalOp(op.Name)
}
func (c *ComputeUtil) deleteDisk() error {
	disk, _ := c.disk()
	if disk == nil {
		return nil
	}

	log.Infof("Deleting disk.")
	op, err := c.service.Disks.Delete(c.project, c.zone, c.diskName()).Do()
	if err != nil {
		return err
	}

	log.Infof("Waiting for disk to delete.")
	return c.waitForRegionalOp(op.Name)
}
// deleteDisk deletes the persistent disk.