trigger STMdeleteFromWithdrawal on Training_Plan__c (After update) {
    
    Set<Id> ids = Trigger.newMap.keySet();
    List<Training_Plan__c> updatedTAs = [Select Id, TEC_Status__c, (select ID, STM_Date__c, 
                                                                    Training_Plan_Withdrawal_Date__c,
                                                                    Monthly_Totals_Name__c 
                                                                    from STM_Computations__r)
                                         From Training_Plan__c
                                         where Id IN :ids];    
    //get collection of STM computaion records to delete
    List<STM_Computation__c> stmToDelete = new List<STM_Computation__c>();
    
    for (Training_Plan__c tps : updatedTAs){
        String oldValue = Trigger.oldMap.get(tps.Id).TEC_Status__c;
        String newValue = tps.TEC_Status__c;
        
        if(oldValue != newValue){
            for (STM_Computation__c stm: tps.STM_Computations__r){
                if(stm.STM_Date__c>stm.Training_Plan_Withdrawal_Date__c){
                    stmToDelete.add(stm);
                }
            }
        }
    }
    
    //get collection of Monthly Total ids to delete
    set<id> mtsIds = new set<id>();
    for (STM_Computation__c stms : stmToDelete){
        mtsIds.add(stms.Monthly_Totals_Name__c);
    }
    
    List<Monthly_Totals__c> monthlyTotalsToDelete = [Select Id From Monthly_Totals__c
                                                     where Id IN :mtsIds];    
    //Delete STM Computation records  
    if(!stmToDelete.isEmpty())
    {
        delete stmToDelete;
    }
    //Delete Monthly Totals records   
    if(!monthlyTotalsToDelete.isEmpty())
    {
        delete monthlyTotalsToDelete;
    }
}