Google Now is malware that can't be removed and is constantly showing you ads and spying on your behavior (look at the app integrations menu). The best you can do is go through the disable-athon menu, but that only works until the next update.
It's an impressive bit of technology though, I've never seen an app so good at telling me exactly what I didn't care about, exactly 10 minutes after I would have cared about it.
If it can't be deleted then it's not optional. Even disabling it is obfuscated behind signing out, but I don't know if it still sends data to google or not.
It's an impressive bit of technology though, I've never seen an app so good at telling me exactly what I didn't care about, exactly 10 minutes after I would have cared about it.