Filter pivot by date

I need to figure out how to filter the pivot table in the attachment by the Posted date. I only want to look at the data for dates within 30 days of today, and can't figure out how to do that manually, much less programatically. The attachement is a small sample of a huge report I receive; all I get is the pivot, which contains tons of information. I filter it down by my various criteria, but that's still hundreds of thousands of lines. Limiting to the last 30 days can make a huge difference, but I can't find the trick to it. Any help is greatly appreciated.

Thanks,
John