When you are located at the front page you can navigate to the settings icon, down by the text where it says Booking open.
It will then open a menu, where you’ll be able to switch the online booking on/off at specific times. You can also turn off online booking for that day completely. Remember this will not interfere with manual bookings or already booked bookings.
Once the changes have been made, it’ll show up as Modified times, which means that your choices now have been saved in the system for that specific day.