You have to pay the guy who runs the site to remove it or attempt to sue him like others have tried. Or what some companies do is get it pushed down in search results by getting other sites to rank for their name, like facebook, linkedIn, YouTube, and various company profile page options.
Rippoffreport claims to be very pro-consumer which leaves many legit businesses getting fake reports against them. Some say it's a total scam to pull money from the businesses. A bad report is put up and it doesn't matter if you can provide 100% proof it's fake, it's takes an undisclosed amount of money to get it taken off in all cases I've seen.
It's amazing Google hasn't caught on yet and still gives them so much authority in search results. They do however have a lot of legit rip off claims to give them credit. I have no doubt competitors make reports against each other all the time knowing it will hurt them.