How to make the Business Process flow stage should transition to match with the option set same value in crm 2015

Hi all,

I wrote a plugin to match the option set value with the Business Process flow stage . The problem is that

if we are changing the option set value the stage is changed with the flag notification as active

but the previous stage also notify as selected. I need to remove this previous stage notification.

This is the code i used

 var status = application.asqa_RegApplicationStatus;
            if (status == null) return;
            var processId = application.processid;
            if (Context.PostEntityImages.Contains("PostImage"))
            {
                var postImage = Context.PostEntityImages["PostImage"]
                    .ToEntity<asqa_RegistrationApplication>();
                processId = processId ?? postImage.processid;
            }
            IList<ProcessStage> processStages;
            using (var c = new XrmServiceContext(OrganizationService))
            {
                processStages = c.ProcessStageSet.Where(x => x.ProcessId.Id == processId).ToList();
            }
            var regApp = new asqa_RegistrationApplication { Id = application.Id, processid = processId };
            switch (status.Value)
            {
               case (int)EnRegApplicationStatus.Reviewing:
                    {
                        var processStage = processStages.FirstOrDefault(p => p.StageName == CRMConstants.BusinessProcessFlow.VetMaterialChangeRegistration.Reviewing);
                        if (processStage != null)
                        {
                            regApp.stageid = processStage.ProcessStageId;
                        }
                        break;
                    }
                case (int)EnRegApplicationStatus.Returned:
                    {
                        var processStage = processStages.FirstOrDefault(p => p.StageName == CRMConstants.BusinessProcessFlow.VetMaterialChangeRegistration.Returned);
                        if (processStage != null)
                        {
                            regApp.stageid = processStage.ProcessStageId;
                        }
                        break;
                    }                             
            }
            UpdateEntityRecord(regApp);