In REST API, you would need to abandon a review prior to delete it.
Then delete it with http://localhost:8060/rest-service/reviews-v1/CR-5/transition?action=action:deleteReview, you won't be able to delete it as you are prompted with message "You can't do action:deleteReview in state Dead"
If you run http://localhost:8060/rest-service/reviews-v1/CR-5/transitions, it will listed that the only action allowed is recoverReview.
Hence, looks like action:deleteReview is never achievable.
The actual way to delete a review is DELETE http://localhost:8060/rest-service/reviews-v1/CR-5 which has been abandoned earlier.