Delete thread after certain date?

[BlueNinjaGo]

Is there a way to make a specific board(s) delete threads after x amount of days? I have a few RSS feeds set up from other sites and after a day or two, there's no chance of anyone reading it, so I'd like to have it deleted automatically.

I know there's a mod to automatically CLOSE a thread, but I wish to permanently DELETE it.

Thanks in advance.