While this feature can be handy when you want quick access to recent communication functions, for some it's annoying and they want to turn them off, follow the instructions below to turn off contact history in your multitasking interface.
Disable recent contact history in the App Switcher.
Step 1: Go to Settings.
Step 3: Press on Show inApp Switcher.
Step 4: Turn off both Phone Favorites and Recents items.
Step 5: Double tap the Home button and you'll notice recent contact history is no longer there, similar to iOS 7.
This feature is quite handy and useful, you can refer to the article above to understand more about enabling/disabling contact history in iOS 8 interface. Additionally, you can read more articles about iOS 8 such as Recovering iPhone when power off on iOS 8.
https://Mytour.vn/disable-contact-history-feature-in-ios-8-multitasking-interface-1012n.aspx
Image source: Internet