Remove recent documents history?
It is generated by Spotlight

(see the second post on this link: https://discussions.apple.com/thread/1071627?tstart=0)

You can make it so that nothing shows up (aka deactivating it) by doing the following.


System Preferences > Spotlight > Privacy > +
then select your Macintosh HD (or whatever your HD is called)
then click choose.


Now that should do it.