@Kim433, you can make a cancellation without penalty if you are on Instant Book, but you should contact AirBnB support to do so.
You can still contact them about this cancellation; explain the circumstances of why you cancelled and they will tell you if it can be a penalty-free cancellation.
In the future, to make it easier on yourself, please contact AirBnB support first and let them know why you want to cancel before you do anything with the booking.
Please be nice to the AirBnB support person who is helping you! They will be making the judgement as to whether it can be penalty-free.