One of my client own rpgshow.com.

For the keyword " rpgshow " , the site gets rank #4 in google.

And in the same way for the " rpgshow " keyword,one of his another site " complaintsboard.com got rank #5 so he want to down the rank for complaintsboard.com and get it to page 4 or 5 in search engine.

So what do i need to do to down the rank?

thanks in advance!