How do I delete a Message without opening it first (on computer, no swiping available)

I'm suddenly getting a lot of nasty spam in my Messages. On the iPhone I can just swipe and delete them, but they seem to linger and are still there when I use Messages on my MacBook. Nothing happens when hovering, and "selecting" opens the spam message. It seems I'm forced to open potentially dangerous spam before it can be deleted! Is there any way to delete it directly without opening?