One of iOS 8 features is to show a list most recent contacts in App Switcher. Some users may find this to be convenient, but others may not like this feature.
If you want to remove recent contacts from App Switcher, open Settings, and then go to Mail, Contacts, Calendar, and change Show In App Switcher setting to Off.
That’s it. From now on, App Switcher won’t show recent contact list. To display recent contacts again, just change the setting to On.