Delete a specific NI category for an employee

curl --request DELETE \
  --url https://api.sandbox.flowpayroll.ai/v1/employees/{employeeId}/ni-categories/{year}/{effectiveDate} \
  --header 'X-Auth-Token: <api-key>'

{
  "message": {
    "text": "<string>",
    "token": "<string>",
    "tokenArguments": [
      {
        "name": "<string>",
        "value": "<string>"
      }
    ]
  },
  "content": {
    "data": {
      "name": {
        "firstName": "John",
        "lastName": "Smith",
        "middleName": "Edward",
        "title": "Mr"
      },
      "email": "john.smith@company.com",
      "birthGender": "Male",
      "birthDate": "1985-07-23",
      "hoursWorkedCategory": "Above30Hours",
      "id": "emp_12345",
      "payrollConfigId": "payroll_config_001",
      "starterDetails": {
        "startDate": "2024-01-15",
        "starterDeclaration": "ThisIsMyOnlyJob",
        "secondedDetails": {
          "stayStatus": "Stay183DaysOrMore",
          "eEACitizen": true,
          "ePM6": false
        },
        "alreadySentToHmrcFps": false
      },
      "taxCodesPerYear": {
        "2025": [
          {
            "code": "1257L",
            "effectiveDate": "2025-04-06",
            "reason": "HMRC Update",
            "issuedBy": "HMRC",
            "week1Month1": false
          }
        ]
      },
      "niDetails": {
        "categoriesPerYear": {},
        "nationalInsuranceNumber": "QQ123456C"
      },
      "phone": "+447700900123",
      "maritalStatus": "Married",
      "salary": 35000,
      "employeeCode": "EMP001",
      "secondaryEmail": "john.secondary@company.com",
      "address": {
        "line1": "123 Main Street",
        "line2": "Apt 4B",
        "city": "London",
        "county": "Greater London",
        "postcode": "SW1A 1AA",
        "countryCode": "UK"
      },
      "bankAccounts": [
        {
          "accountNumber": "12345678",
          "sortCode": "123456",
          "allocationPercentage": 100,
          "isPrimaryPayrollAccount": true,
          "accountHolderName": "John Smith"
        }
      ],
      "studentDetails": {
        "studentLoanDetails": {
          "loanType": "Plan2",
          "startDate": "2010-09-01",
          "endDate": "2025-07-31"
        },
        "postgraduateLoanDetails": {
          "loanType": "PostgraduateLoan",
          "startDate": "2015-09-01",
          "endDate": "2028-07-31"
        }
      },
      "tags": [
        {
          "name": "FullTime",
          "group": "EmploymentType",
          "value": "FullTime"
        }
      ],
      "previousEmployment": {
        "2026": {
          "grossTaxable": 15000,
          "tax": 3000
        }
      },
      "gender": "Male",
      "secondaryPhone": "+447700900124",
      "passportNumber": "123456789",
      "previousNames": [
        "John Doe"
      ],
      "directorDetails": {
        "directorsNICType": "Annual",
        "appointmentDate": "2024-01-15",
        "endDate": "2025-03-31"
      },
      "isIrregularEmployment": false,
      "isOffPayrollWorker": false,
      "workplaceDetails": {
        "workplaceId": "workplace_001",
        "workplaceName": "Head Office",
        "address": {
          "line1": "123 Main Street",
          "line2": "Apt 4B",
          "city": "London",
          "county": "Greater London",
          "postcode": "SW1A 1AA",
          "countryCode": "UK"
        }
      },
      "workingDays": {
        "standardWorkingDays": {
          "monday": true,
          "tuesday": true,
          "wednesday": true,
          "thursday": true,
          "friday": true,
          "saturday": false,
          "sunday": false
        },
        "shiftPattern": {
          "rotationStartDate": "2024-01-01",
          "shifts": [
            {
              "name": "Morning Shift",
              "workingDays": {
                "monday": true,
                "tuesday": true,
                "wednesday": true,
                "thursday": true,
                "friday": true,
                "saturday": false,
                "sunday": false
              },
              "durationInDays": 5,
              "weekNumber": 1
            },
            {
              "name": "Night Shift",
              "workingDays": {
                "monday": true,
                "tuesday": true,
                "wednesday": true,
                "thursday": true,
                "friday": true,
                "saturday": false,
                "sunday": false
              },
              "durationInDays": 5,
              "weekNumber": 2
            }
          ],
          "patternType": "FourOnFourOff",
          "patternWeeks": 8
        },
        "workingPattern": "Standard"
      },
      "partnerDetails": {
        "name": {
          "firstName": "John",
          "lastName": "Smith",
          "middleName": "Edward",
          "title": "Mr"
        },
        "nationalInsuranceNumber": "QQ654321A"
      },
      "department": "Engineering",
      "jobTitle": "Software Engineer",
      "leaverDetails": {
        "leavingDate": "2024-12-31",
        "reason": "Retirement",
        "issuedBy": "Employer",
        "reportedToHmrc": false
      },
      "earningsToDatePerYear": {},
      "openingBalance": {},
      "openingBalanceDirector": {},
      "directorEarningsToDatePerYear": {},
      "payrollId": "PAY123",
      "createdDate": "2023-01-15T10:00:00Z",
      "createdBy": "admin@company.com",
      "updatedDate": "2023-06-01T12:00:00Z",
      "updatedBy": "hr@company.com"
    },
    "metadata": {
      "dateFormat": "yyyy-MM-dd",
      "dateTimeFormat": "yyyy-MM-ddTHH:mm:ss.fffZ",
      "paginationToken": "<string>"
    }
  },
  "validationIssues": [
    {
      "field": "<string>",
      "reason": "<string>",
      "reasonToken": "<string>",
      "reasonTokenArguments": [
        {
          "name": "<string>",
          "value": "<string>"
        }
      ]
    }
  ],
  "messageToken": "<string>"
}