public function removeEmployeeByCardNumber($cardNumber)
    {
        $cardNumber = $this->prepareKey($cardNumber);
        $result     = null;
        $this->addHeader();
        try {
            $empResult = $this->getSoap()->GetAssignedAcsKeyByKeyNumber([
                'keyNumber' => $cardNumber
            ]);
            if ($empResult->GetAssignedAcsKeyByKeyNumberResult !== null) {
                $result = $this->removeEmployee($empResult->GetAssignedAcsKeyByKeyNumberResult->AcsEmployeeId);
            }
        } catch (\SoapFault $ex) {
            $this->logError();
        }
        return $result;
    }