Cancellation as a host

[Ghada4]

Hello, I have the option "instant booking" and I don't know how to change it. I prefer to have the option to confirm or not before booking is made by a guest. 

Couple of minutes ago I received a request for booking for dates when I'm not available, and I didn't pay attention that these dates were indicated available on my calendar. So the booking was made by the guest, but I will have to cancel it. However, I shouldn't be charged, since it will be cancelled within 24 hours. So how should I do this? How can I cancel for free? (I already informed the guest). and how do I change the setting to cancel the "instant booking". 

[Emiel1]

@Ghada4 

If you would have put "instant book" as search keywords on the Airbnb HELP, you would have found this:

https://www.airbnb.com/help/article/1510/how-do-i-turn-instant-book-on-or-off

There is no time limit for hosts to cancel a booking penalty free (only for guests depending on cancellation policy). The only option you maybe have to not be penalised is try to contact Airbnb and ask them to cancel, explaining you made a mistake.:

Contact Airbnb - Community Guide [Updated]

Hope this helps,

Emiel