User threatening to destroy the site

Ok I've got a bit of a problem and I'm not sure how to deal with it. Someone keeps creating accounts and spamming topics with insults and vulgarity in the site I'm on. Everytime one of the accounts gets banned he makes another that seems real enough, but then he starts all over again. He says that he'll destroy the site by making everyone lose trust in new members. How do we deal with this troll?

Just keep banning him until he gets bored also ban his IP address.

One solution for this problem is to hire more moderators to ensure the security and cleanliness of the forum, this way, it'll be harder for him to spam/attack if there are moderators online to ban him and secondly, keep banning him, he'll eventually go away. IP ban him if needed.

You may wish to IP ban him or her.

Go to Users & Groups => Ban Control => Ban IP => Search for user IP address => Ban.

Make sure you also keep deleting their posts & topics so that they can no longer view them. Think these idiots like to see their stupidity "immortalised" in forums. It takes some of their weird pleasure away if these are deleted.

You will just have to be vigilant until they get bored, as Maki1 said, & move on to the next target. These sort of trolls would, hopefully, tend to have a short attention span. You just have to outlast them.

Another thing to do if this idiot is persistent, could be to place your forum in Construction or Holiday mode for a short time. AP>General>Forum>Configuration>Forum in construction (or Holiday) click Yes>Save. You won't get any new members during this time & your current members won't be able to post. Just warn them this is happening if you trust them. But you will stop these malicious accounts being made.

Make new members activated by Administration only, not self-activated.