How do I close a thread?

I've been on guru for years, and still dont' know how to close a thread... Help?

Ask a moderator. Either post something like "Please close," or edit one of your posts to ask for a close. You can also send a PM to a moderator requesting a close. You'll find a list of the moderators in each section of the forum in the bottom right. Full list of the moderators can be found here.

Moderators can close threads in the sections they moderate, supers mods and admins can in all areas. For the most part you must ask someone to close the thread for you.
If you need a thread closed...simply put "thread closed" or "please close thread" in the original post. You are allowed to have multiple threads open in most areas of guru EXCEPT Ventari's where you are only allowed ONE open thread per section (the guidelines for Ventari's can be found at the top of each of its sections in a sticky).

I think the idea is that once you post a thread (outside of ventari), it isn't really yours, it belongs to the community at large.

You can't. Ask a mod like posted above to close it if you realy really don't want people posting in it anymore; but otherwise, just let your threads die away.