How to deal with out dated posts?

Hello,


I'm struggling with the following.


Every month I want to add a post with the best selling products in my niche.
I also want to do this with the best deals and highest discounts for the products every month.


But how do I post these posts?


I mean, if I add a new post every month called like:
Best Selling X Products in June 2012
Best Selling X Products in July 2012
etc.


After two years I have a lot of these posts on my website that are not relevant anymore. Google let us know that they want us to remove these old posts and pages from our website.
What is the best way to deal with this?

I think it's also not good to remove all these pages, but I would like to know how to handle this.


Should it be better to post these best selling products from each month on one single post and add every month the new month on top. I want to keep about 6 months on the post, then every time I post a new month, then delete the oldest one at the bottom.
Do you think this will work?


I hope you want to share with me how you deal with this.


Thanks a lot,


Isaan