How do I remove the "Articles" bit on the search widget ?

Greetings,

The "Social" theme is great, but there is just one thing :

The search widget has a dropdown menu that allow people to choose between "articles" and other searches...

Thing is, on my blog network there is no articles, just pages... So 2 things :

1) Is that search widget functionnal in that context (will people be able to search efficiently) ?

2) How do I remove the "Articles" dropdown menu, since it's of no use since people don't have a choice...

Here's a picture to explain what I mean :
https://dl.dropboxusercontent.com/u/5140132/wpmu/remove-articles-in-search-bar.png

Thanks a lot for your help !

DJ