This method rejects the posted merchant payout due to various reasons, and this is applicable for 4-eye and 6-eye principle workflows. For payload explanations for both request and response, click here 
using OneKhusa.SDK; 
using OneKhusa.SDK.Models.Transactions.SingleDisbursements; 

//code omitted for brevity 

OneKhusaResponse<RejectPayoutResponse> response = await client 
    .Transactions 
    .SingleDisbursements 
    .RejectPayoutAsync(new RejectPayoutRequest 
    { 
        TransactionReferenceNumber = "260219YXF882", 
        MerchantAccountNumber = 12345678, 
        ReasonForRejection = "The beneficiary is a defaulter", 
        RejectedBy = "joe.doe@example.com" 
    }); 

if (response is { IsSuccess: true, Data: not null }) 
{ 
    Console.WriteLine($"Message: {response.Data.Message}"); 
    return; 
}
//it means an error occurred 
//Get error details from response.Error
Note: This method accepts custom idempotency key generated by your system. By default, if not specified, it will create one on your behalf.