Hello @Mohsin12
Airbnb expects us as hosts to keep our listings up to date including our prices. As others have mentioned why should the guest be penalised because you didn't review your pricing when you opened up your calendar.
I would take this as a lesson learned and always make sure you review your pricing when opening up your calendar.
If you cancel, Airbnb will block the dates, so you might as well keep the booking you have.