code: protected function removeAssignment(StockAssignmentInterface $assignment)
      {
          $this->unitUpdater->updateSold($assignment->getStockUnit(), -$assignment->getSoldQuantity(), true);
  
          $assignment
              ->setSaleItem(null)
              ->setStockUnit(null);
  
          $this->persistenceHelper->remove($assignment);
      }
docs: Removes a single assignment.
  
  @param StockAssignmentInterface $assignment