Siri on iOS 9 is smarter than ever and can suggest you apps, contacts, location and more based on your behavior. To disable and turn off Siri app suggestions on iOS 9, do as follows:
1. Open the Settings menu on your iPhone or iPad
2. Go to the General settings
3. Tap to open the Spotlight Search settings (it's under the Siri settings)
4. Now, to turn off Siri suggestions, you just need to toggle off the Siri suggestions option.
Note that the Siri App Suggestions appear when you open the spotlight search by either swiping right from the first home screen or swiping down from any home screen.