@Lindie0
You must ask the guest to cancel the reservation themselves as you cannot cancel for them. If you get an automated message saying the guest requests to cancel, do NOT accept as this is counted as a host generated cancellation and you may have penalties. When they successfully cancel you will just receive a notification that they have done so.
If the guests are having difficulty you can pass along a contact number or phone Airbnb yourself and ask them to reach out to the guest. Do not refund them any money as it must go through the system. They will be refunded in accordance with your cancellation policy.
contact airbnb a community help guide
You have not reached customer support here, just a forum where users can help each other out. Hopefully the support centre can help the guest to cancel, Lisa