Removing spotlight icon from menu bar persistently
This works at least up to 10.9.2.

To disable:

sudo mv /System/Library/CoreServices/Search.bundle /System/Library/CoreServices/Search.bundle.bak
killall SystemUIServer


To re-enable:

sudo mv /System/Library/CoreServices/Search.bundle.bak /System/Library/CoreServices/Search.bundle
killall SystemUIServer