There is a rule on trolling so it is not allowed in the forum but it is not a too severe rule violation. Hence an account that has trolling posts likely won't be banned instantly like with plagiarism. Anyway if you see trolling posts, you can do two things: report those posts to forum moderators for deletion; and don't feed the troll.

If you reply to trolling posts, you are feeding it and make trolleys more exciting and have motivation to continue trolling.