There is no way in the system preference to remove the spotlight icon/functionality from the menu bar. But there is a quick terminal hack that allows you to get rid of it. Open up a terminal window and type the following:

sudo chmod 0 /System/Library/CoreServices/Spotlight.app

an hit Enter. You'll need root access to your machine, and you'll be asked for a password. Once this command runs, enter this in the terminal:

killall Spotlight

and hit Enter again. Once you do this, spotlight will be gone from your menu bar. To get spotlight back, enter these commands in the terminal window

sudo chmod 755 /System/Library/CoreServices/Spotlight.app

and then

killall Spotlight

When you re-enable spotlight, you might get a warning like this:

No matching processes belonging to you were found

but don't worry, after a couple of seconds your spotlight icon will show up again in your menu bar.