memory management of Lists Of Objects

Given Class with:

1- private 
    FCustomerOrders : TList<TCustomerOrders>;
2- on constructor Create;
   FCustomerOrders := TList<TCustomerOrders>.Create;
3- On Load :
  FCustomerOrders := fmanager.Find<TCustomerOrders>.Where(TLinq.Eq('custID',Value)).List;

Should I destroy FCustomerOrders  on destructor  Destroy or it handled By the fManager?

Yes, you should destroy the list. You don't need to destroy the objects in the list, but the list itself must be destroyed.