Siri with no doubt is amazing, but it doesn't mean you cannot disable Siri on iPhone and have to live with it. To turn off Siri on iPhone 6 and iPhone 5 and of course other iDevices, do as follows:
1. Open the Settings app on your iPhone (or iPad)
2. Go to the General settings
3. Tap the Siri option
4. Now all you need to do to disable and turn off Siri on iPhone 6, is toggling off the Siri button and confirm the Disable Siri message.