If you cancel as a host you will be penalised by AirBnB - financially and it will appear on your listing so guests are less likely to book.
Really the time to read previous reviews on your guest is before you accept the booking not after - I'm sure you realise this now 🙂
Best thing is to call BnB say you are a new host and are concerned about the guest - because of whatever issues in the review made you uncomfortable.
See if they might be flexible with you.
Do familiarise yourself with how BnB works and it will help you enjoy your hosting experience and understand your rights and your responsibilities.