@Jenny247 when the guest sends you that kind of message where the guest wants *you* to cancel, decline it.
Then send a message to the guest telling them that the *guest* needs to cancel.
Tell them if they send the message where they are asking the host to cancel, you will decline it every time because the guest needs to cancel.
Repeat until they understand.
If they don't cancel, then they never get their refund. The guest will eventually cancel.
If they try to claim something different with Airbnb support, show Airbnb support the message thread where the guest is the one wishing to cancel.