Disable Spotlight

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist
sudo mdutil -a -i off

Re-enable Spotlight

sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist
sudo mdutil -a -i on

Hide Spotlight from the menubar

sudo chmod 600 /System/Library/CoreServices/Search.bundle/Contents/MacOS/Search
killall SystemUIServer

Show Spotlight on the menubar

sudo chmod 755 /System/Library/CoreServices/Search.bundle/Contents/MacOS/Search
killall SystemUIServer