Is it possible that only thread starters can edit/delete their threads in a certain board?

As far as I know only the ADMIN has that ability. And Moderators have that ability in the forums they are allowed in.
But you do have a feature called "Edit post time limit".
That would allow the user to edit or delete during the timeframe allowed. After the time has expired they can't alter the post anymore.
As a user that feature is enabled here. Until the time limit has expired(Whatever it is) You can edit or delete your post. After the time limit is exceeded you can't alter it anymore.

Hmm. Timeframe is not an option. Because it's a trader board and every trader should have the ability to alter/delete its own thread, but not the one from the others. Regular users which are not part of this group should only have the ability to read, but this isn't a problem with the current rights system.

I added a permission for 7.4.1.SD board that allows just what you want.

'CAN_DELETE_OWN_THREAD' -- and it's also on a forum by forum basis too..

reason it was needed was for a classifieds forum, where the user could remove his classified ad after the item sold or for whatever other reason..

so it's doable, but definitely a modification to stock..

I've sent you a PM regarding the issue. Maybe it's possible to add it in future releases?

Yes I agree I can see the need for some sites. I can also see the other side of the coin where many sites do not ever want such an action to be possible. Having it available in stock code but OFF by default and a popup Warning if you do enable it might be a good addition to the stock code.

Sounds like a good suggestion :-) +1 here