We're a little society here, and societies ostracize those who don't belong. One way is by ignoring them.
The initial reaction to a troll is anger, but that just feeds the troll. Over time, they're seen for what they are, made fun of, then paid less and less attention. When they're ignored--not fed, they'll go away. Newbies will fall for it, but catch on.
Report them, but reports on trolling will be considered only if you can point out violations of rules. Mods trying to deal with them just feeds them, too, given attention, they'll troll you all more and more.
It might be fun, sometimes, to make one dance, but that too just feeds them.
So do nothing--ignore them, they'll get bored, and go elsewhere.
Never wrestle with a pig. You get dirty and the pig enjoys it.