In SharePoint 2010, on the left side of the page (on certain pages), you’ll see a section titled ‘Recently Modified’. There are times when you really either don’t want or don’t need that to show. Luckily, there’s a very easy way to take care of this situation.

All you need to do is to run SharePoint Designer 2010 and open your site. Then, load the master page for your site. Search the page for a placeholder with the id ‘PlaceHolderLeftActions‘. You need to make this not visible. Add this attribute to the placeholder:

visible = "false"

This will (as you might suspect) make that placeholder invisible and solve your problem.

Also, if you want to do this with a CSS solution, you can add a selector to your CSS file that loads, or add it to any one or more pages via a Content Editor Web Part:

.s4-recentchanges
{    
   display:none;
}