How to invoke AR Document (AR Payment) Delete via api Action

I should point out that typically 204 is a success-ish status, but the AR document with the ref number is not removed. 

When I delete the AR Document from the UI, it is, of course, removed from the list of AR Documents.

You need to use ‘DELETE’ type of request instead of ‘POST’

Thank you. If there is something to read in the knowledge base on this, I will look through that. I’m not finding much on Deletes specifically. I think I am close. But it is reporting "Operation is not valid due to the current state of the object."

This is the current state of my payment in the UI. I could use the delete icon here. It does have a Document to Apply entry, if that is relevant.

The current state of my request.
DELETE entity/.../20.200.001/Payment/Delete
BODY {
  "entity": {
    "ReferenceNbr": {
      "value": "068371"
    }
  }
}
RESPONSE 500 

{

"message": "An error has occurred.",

"exceptionMessage": "Operation is not valid due to the current state of the object.",

"exceptionType": "System.InvalidOperationException",

"stackTrace": " at PX.Api.ContractBased.EntityService.FillEntityImplWithKeys(String version, String name, EntityImpl entity, String[] keys)\r\n at PX.Api.ContractBased.AspNetCore.CbEndpointFeatureServiceExtensions.FillEntityImplWithKeys(IEntityService entityService, ICbEndpointFeature feature, EntityImpl entity, String[] keys)\r\n at PX.Api.ContractBased.WebApi.Controllers.EntityController.CreateEntityFromKeys(String objectName, String idsString)\r\n at lambda_method(Closure , Object , Object[] )\r\n at Microsoft.AspNetCore.Mvc.Internal.ActionMethodExecutor.SyncActionResultExecutor.Execute(IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)\r\n at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeActionMethodAsync>d__12.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeNextActionFilterAsync>d__10.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)\r\n at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)\r\n at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeInnerFilterAsync>d__13.MoveNext()\r\n--- End of stack trace from previous location where exception was thrown ---\r\n at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.<InvokeNextExceptionFilterAsync>d__24.MoveNext()"

}

What is this response trying to tell me? Do I need to handle the DocumentToApply separately, or $expand into it like I would with an InsertUpdate?  

I’ve also tried a few variations on the theme

DELETE /Payment  
BODY {

  "entity": {

    "ReferenceNbr": {

      "value": "068371"

    }

  }

}
RESPONSE 500 "Object reference not set to an instance of an object.",

DELETE /Payment/068371 
BODY <EMPTY> and with same body used above.
RESPONSE 500 "Operation is not valid due to the current state of the object”

Thank you. I finally tried.

DELETE /Payment/e734ff7e-fadb-ea11-8177-c9aeb77cfe99
BODY <empty>
RESPONSE 204

For whatever reason, only this variation actually removed the record from the system. Regardless, my issue is resolved, thank you once again for your time.