A mod is there to warn the people to remain on topic, that is part of our tasks. We are here to keep the threads organized. We respect the wishes of the posters, but if it gets too far from the original topic of the thread, then we usually warn the people to stay on track with the discussion.
A regular member has no right to say this, as it would be pseudo modding and should be reported if anything. So, if a member is saying that it is off topic in "your" or any other thread, inform a mod.
If you see a member going off from your topic, inform a mod and we'll handle it as well.