About self moderation.

[LoyceV]

So how someone can remove or delete a topic that he started if he thinks it's irrelevant or unnecessary right now?

You can't. It's not up to you to decide your topic is irrelevant to someone else, that would for instance make it easier for scammers to cover their tracks.

I think there must be some procedure to do that because there are many topics in the service and marketplace board which is created for short time. Or just leave it by thinking it's not there.

If you're a honest trader, keeping records of past trades is actually beneficial for your reputation. If a thread served it's purpose (because you found what you're looking for): just lock it (bottom-left). If you think it not worth keeping on that board, move (bottom-left) it to Archival.

If you initially create a self-moderated topic, then you can delete it later.

Nope, you can't. I just tested it.

[Razmirraz]

I think @LoyceV has answered the Op question completely.
I hope the Op can understand the whole explanation from @LoyceV above my writing. Op, what you are looking for you have founded. Immediately lock this thread to prevent a discussion that strays from the topic.

[Igebotz]

I wonder why it's so.

Deleting a thread would mean you get to delete someone else's posts.

But of course, I know. It's the same way when mods take down threads they (by their judgment) think it's unnecessary or that infringed on certain rules. If mods can do that, why can't thread starters themselves? That's the area of my puzzlement.

Because Mods ensure that the threads reported for deletion have no informative posts or a large number of posters on them before deleting them, they don't delete a thread just because you reported it to be deleted; if they find some useful information on the thread, they usually move it to archive or lock it. If the same privilege is granted to every threads starter, it will be abused.

If posters had the ability to delete threads, most of the historical threads we refer to today, such as the Pizza, Bitcoin and Me and most Bitcoin posts, would have been deleted by the poster prior to leaving the forum. Leaving us with no history

[Mpamaegbu]

If posters had the ability to delete threads, most of the historical threads we refer to today, such as the Pizza, Bitcoin and Me and most Bitcoin posts, would have been deleted by the poster prior to leaving the forum. Leaving us with no history

Yeah, I realized that later too. Now I see why it's better that the privilege to delete threads isn't granted to thread openers, except moderators. It saves the forum lots of educational and historical posts and threads that ordinarily would be lost by that action. I acknowledge that sometimes the urge to do away with threads one feels aren't worthy anymore or shitty may come up but like LoyceV said it's best to move them to the archive.

[dkbit98]

So how someone can remove or delete a topic that he started if he thinks it's irrelevant or unnecessary right now? I think there must be some procedure to do that because there are many topics in the service and marketplace board which is created for short time. Or just leave it by thinking it's not there.

You can try asking moderators to delete your topic but it's not likely they will have the time or the will to deal with that.
Best thing you could do is locking the topic and moving it to archive section of the forum, and deleting all your post from that topic.
All this can be done for privacy reasons, but note that everything in forum is archived and saved all the time, so it's not easy to hide something you once wrote.

[The Sceptical Chymist]

If you're a topic starter or topic creator, there's no way to delete it but you can be able to edit, move your topic to Archival (the trashcan section)<snip>

Is there any advantage to moving an obsolete thread to Archival as opposed to simply deleting the posts and then locking it?  I assume the thread would either disappear into the deep depths of whatever section it was in, or the mods would delete it eventually.

Thanks for bringing up the move to Archival, by the way.  I've deleted my own posts from threads I've started and then locked it up, but I never considered your suggestion before.  In fact, I've been here 7 years and I don't think I've ever manually moved a thread to another section before, even though there have been times I probably should have.  Neat-O.

[sheenshane]

If you're a topic starter or topic creator, there's no way to delete it but you can be able to edit, move your topic to Archival (the trashcan section)<snip>

Is there any advantage to moving an obsolete thread to Archival as opposed to simply deleting the posts and then locking it?  

I never tried either.

I've searched your name on Archival it seems you're right, you never move your topic starter there.
IMO, Archival is considered as a trashcan board which is no one will visit there if you have a thread that you've started and delete the body, maybe it will take a long time before it will disappear or go into deep depths.  The advantage could be, we help to lessen the task of moderators deleting that thread that we started, maybe it will take a long time they will delete the thread even if we already deleted and reported, moving to the trashcan board would be good, IMO.