Client wants to delete negative reviews/posts.

My client has a product that has some bad reviews for slow shipping. After doing some research he has tons of sites who are saying the same thing. Ie ripoffreport, various forums and blog posts. I told him it was a long shot to get these removed because these are all independent websites that I don't control. Thus here I am. Is there anything I can do to help this guy?

If they can't be removed whats a way I can combat the issue for him? I was thinking about writing good posts/reviews but that would take time to push down the old stuff.

That's pretty much what I recommend you to do, you need to flood the place with positive reviews. There are many ways to do this. Offer the people in your area free products in exchange for a positive review. Create websites vouching for the site, etc. Much easier to create than to destroy. All up to you in the end. Read up more on PR and reputation management. Make sure you are aware of all laws regarding manipulation of reviews and such!

Also welcome to BHW, it is great to see people who are already fairly familiar with IM joining BHW.