I think in a new update, Clan Managers should be able to archive or delete some threads, or either mark them as completed/resolved. Then these threads would be available from another page.

i agree especially when it comes to new members joining ... this way only the important and active threads are there and they are not overwhelmed with all the topics that are going on .. also it will make the clan forum more neat and attractive as well

Put it on Uservoice! I also agree, and willing to put some votes on it.

I'm the right hand of Cheshire and we don't use Uservoice. But tomorrow, we'll see.

Here:
http://warlight.uservoice.com/forums/77051-warlight-features/suggestions/4875611-archive-clan-s-forums-

nice idea... also i would think it would not be to hard to code

Please vote. I'm sure this idea will help almost all the clans.