For some reason 12 august I have availability 9 A-houses But I only have FIVE

I want to block this date so when this person cancel those 4 houses, no one else can book them.

If I go to the calender and close 12 august and the person cancel those 4 houses then they will appear again 12 august even though I have this date closed.

What can I do so no one can book 12 august when they cancel there reservation (Alej AleB 2982125475)

Best regards