Hi Bear

Following (after) your login workflow you can add this workflow, it deletes the record and you can optionally choose "Retain the delete workflow when deleting".

You may find that the delete works better on the approved action, after the form is recorded fully, so try automatically approving the form, and then move at least the delete workflow to the Approved action.

This is my delete workflow and feel free to change the Namespace to suit your project...

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using umbraco.BusinessLogic;
using umbraco.cms.businesslogic.web;
using umbraco.cms.businesslogic.property;
using umbraco.cms.businesslogic.propertytype;
using Umbraco.Forms.Data;
using Umbraco.Forms.Core;
using Umbraco.Forms.Core.Enums;
using Umbraco.Forms.Core.Services;
using Umbraco.Forms.Data.Storage;
using umbraco.DataLayer;

namespace RDL.Contour.WorkFlows
{
    public class DeleteRecord : WorkflowType
   {

        public DeleteRecord()
        {
         this.Id = new Guid("93bee308-dbc0-41ee-80ec-aeef83914330");
           this.Name = "Delete record";
          this.Description = "Delete Record.";
      }

        [Umbraco.Forms.Core.Attributes.Setting("Delete", description = "Retain the delete workflow when deleting", control = "Umbraco.Forms.Core.FieldSetting.Checkbox")]
        public string Delete { get; set; }

  public override WorkflowExecutionStatus Execute(Record record, RecordEventArgs e)
 {
                
            if (Delete == true.ToString())
            {
                Umbraco.Forms.Data.Storage.RecordStorage storage = new Umbraco.Forms.Data.Storage.RecordStorage();
                Umbraco.Forms.Core.Record targetRecord = record;
                Umbraco.Forms.Core.Form targetForm = new FormStorage().GetFormFromRecordId(record.Id);
                Umbraco.Forms.Core.Services.RecordService rs = new Umbraco.Forms.Core.Services.RecordService(targetRecord);

                storage.DeleteRecord(targetRecord);
                storage.Dispose();

                //Log.Add(LogTypes.Custom, 0, "Record deleted with Workflow");

            } else {

                var x = SqlHelper.ExecuteNonQuery("DELETE FROM UFRecords WHERE Id= '" +record.Id.ToString()+"'");

                if (x > 0)
                {
                    //Log.Add(LogTypes.Custom, 0, "Record deleted");
                }
                else
                {
                    //Log.Add(LogTypes.Custom, 0, "Record delete failed");
                }
            }
            return WorkflowExecutionStatus.Completed;
    }

   public override List<Exception> ValidateSettings()
  {
     return new List<Exception>();
   }

        protected static ISqlHelper SqlHelper
        {
            get { return umbraco.BusinessLogic.Application.SqlHelper; }
        }
 }
}

Hope this helps!

Cheers
Josh