Moderators can delete comments from Q&A pages by hovering over them; a red link appears, similar to how deleting one's own comments works:
However, this functionality is not available in the review queues. Can it please be added? It is possible to flag a comment as No Longer Needed, but that takes an extra click and more mouse movement.
This is similar to Can't delete own comment when revisiting Close Vote review page but that only happens when viewing a completed review queue item; this also pertains to active review queue tasks.