global class DeleteBulkRecordBatch2 implements Database.Batchable<SObject>, Database.Stateful {
    
    String query = '';
    String sObjectType = '';
    List<String> list_Employee= new List<String>();
    Date FROM_DATE = Null;
    Date toDate = Null;
    Set<Id> set_nonDeleteId = new Set<Id>();
    
    // Constructor
    //sobject type=Employeer(account),Contact
    global DeleteBulkRecordBatch2(String sObjectType, List<String> list_Employee,Date FROM_DATE,Date toDate){
        this.sObjectType = sObjectType;
        this.list_Employee = list_Employee;
        this.FROM_DATE = FROM_DATE;
        this.toDate = toDate;
        
    }
    global Database.QueryLocator start(Database.BatchableContext bc){
        

        
        if(sObjectType == 'Order'){
            if(FROM_DATE == Null && toDate == Null ){
                query='Select Id,account_holder__r.Account__c,account_holder__r.AccountId from Order__c WHERE account_holder__r.AccountId=:list_Employee';
            }else{
                query='Select Id,account_holder__r.Account__c,account_holder__r.AccountId from Order__c WHERE (account_holder__r.AccountId = :list_Employee) AND (NOT (LastmodifiedDate >=:FROM_DATE AND LastmodifiedDate <=: toDate))'; 
            }
        }else if(sObjectType == 'Contact'){
            if(FROM_DATE == Null && toDate == Null ){
                query='Select Id,Account.id,Account.name,Account__c,Parent_Member_Name__r.id,(Select Id from cases),(select Id from Contact_Products__r) from Contact WHERE Account.id=:list_Employee';
            }else{
                query='Select Id,Account.id,Account.name,Account__c,Parent_Member_Name__r.id,(Select Id from cases),(select Id from Contact_Products__r) from contact WHERE ((Account__r.Instructing_Party__c =:list_Employee) OR (Account.id = :list_Employee)) AND (NOT(account__c =:set_nonDeleteId)) AND (LastmodifiedDate >=:FROM_DATE AND LastmodifiedDate <=:toDate)';
       }
        
        }
        System.debug(query);
        return Database.getQueryLocator(query);
    }
    global void execute(Database.BatchableContext bc, List<SObject> s_object){
        System.debug('--execute---');
        System.debug('--set_nonDeleteId---'+set_nonDeleteId);
        System.debug('--list_Employee---'+list_Employee);
        
        if(sObjectType == 'Order') {
            List<order__c> list_Order = new List<order__c>();
            // todo=merge both the for Loop
            for(SObject obj : s_object){
                order__c order  = (order__c)obj;
                list_Order.add(order);
                 System.debug('--list_Order---'+list_Order);
            }
                for(Order__c obj_Order : list_order){
                    set_nonDeleteId.add(obj_Order.Account_Holder__r.account__c);
                    System.debug('--set_nonDeleteId---'+set_nonDeleteId);
            }
        }else if(sObjectType == 'Contact'){
            List<Contact> list_contact = new List<contact>();
            List<Case> list_Case = new List<Case>();
            List<Contact_Products__c> list_Contact_Products = new List<Contact_Products__c>(); 
            for(SObject obj : s_object){
                Contact contacts  = (contact)obj;
                list_contact.add(contacts);
                System.debug('--list_contact---'+list_contact);
                for(Case c : obj.cases){
                    Case Cas  = (Case)c;
                    list_Case.add(Cas); 
                    System.debug('--list_Case---'+list_Case);
                }
                for(Contact_Products__c Contact_Products : obj.Contact_Products__r){
                    Contact_Products__c ContactProducts  = (Contact_Products__c)Contact_Products;
                    list_Contact_Products.add(ContactProducts);
                    System.debug('--list_Contact_Products---'+list_Contact_Products);
                
                }
            }
            delete list_Case;
            delete list_Contact_Products;
            delete list_contact;
            
        }
        
    }       
    global void finish(Database.BatchableContext bc){
        if (sObjectType == 'Order') {       
            Id batchJobId = Database.executeBatch(new DeleteBulkRecordBatch2('Contact',list_Employee,FROM_DATE,toDate), 1000);
       
        }
    }    
    
}

Variables does not exist: cases
Variables does not exist: Contact_Products__r

these two errors are coming in this code, how to resolve this
please tell me where I'm missing
Thanks in advance