@Marina741,
You (or the guest) can change the reservation by shortening it and price will be recalculated. If calculation is not OK, you can put in a price manually (for example weekly discount will not appy, cancelation policy doing unwanted things etc..). So that's why it's better you do it, to stay in control.
https://www.airbnb.com/help/article/50/i-m-a-host--how-do-i-make-a-change-to-a-confirmed-reservation
An other option is: the guest cancels the reservation and try to get a refund at Airbnb due to "extenuating circumstances"
https://www.airbnb.com/help/article/1339/how-do-i-file-an-extenuating-circumstances-claim
Both options do not relate in becoming Superhost, it's just a business deal.
BTW Never cancel the reservation yourself !
Best regards,
Emiel