Removing their low quality comments won't hurt them. It'll only help them to be more constructive but it's your call.
From my experience that doesn't work. If you remove this spammy posts they will learn nothing only make them angry and maybe leave the forum or fight against it in the worse scenario. We need to educate them using the karma points, I assume.If you spot such a spammer then give negative karma. If he gets enough, he will have to do something about it and come to the court, were i will try to educate him on posting or he will improve by himself, when he will see, that actual strategy doesn't work at all.
You can always send a PM after such negative karma, that you will adjust it with an positive, if he edit (if possible) his spammy post or write a new one and inform you about this.
I know is a lot additional work, but such approach to newbies and spammers will work the best, to not scare them off from the forum, because we need more members, even if they are low quality once. Our mission is to transfer them, into high quality members.