You don't only have to terminate someone only if they are displaying bad behaviour. You are terminating because this is the best decision for your business - nothing personal and no bad feelings.
I just had a parent give notice earlier than I expected. It was the best scenario for HER and I didn't take it personal, though in my early years of daycare I would have. Even though most of us have good clients, no one is going to stay if they don't need to, no matter how much they like us. The clients are going to do what suits them always and as a business person, you need to do what is best for your business, always.