It is not possible to delete a review after it has been submitted to Airbnb.
You can cancel a review that is prepared for a guest and has not been submitted to Airbnb.
Go to Guest experience
In the Overview section, click Pending reviews
Click on the review name to open the prepared review
Click Delete
You can also find the prepared review on the conversation page with a guest, listed under the Activity section on the left-hand panel.