Apart from a few additions like widgets, iOS 8 is – interface-wise – more or less the same as its immediate predecessor iOS 7. But one of the additions that make reaching out to your favorite contacts faster is the contacts menu in the task switcher.
Unlike in iOS 7, where the whole section was empty, contact pictures are now shown above the app switcher in iOS 8. It's a quicker way to communicate with people in your favorites/recent list (from the Phone app). But not everyone wants to see this in the task switcher. If you want to remove contact pictures from iOS 8's task switcher, here how to do that:
Step 1: Open Settings
Step 2: Tap on Mail, Contacts, Calendars
Step 3: Scroll down, and under the label Contacts and tap on Show In App Switcher
Step 4: Toggle off Recent and Phone Favorites
That’s all there is to it! You have now successfully removed the contact pictures from showing above the app switcher. You can reverse the same step if you want them back again.
The sole objective of the contact pictures showing above the app switcher is to let you have an easy access to your favorite contacts. You can easily communicate or chat with the people you want to communicate just by tapping on the contact picture.
But it's not without its cons. First off, not everyone's comfortable with their contacts' pictures showing up in a screen that's accessible easily. If someone other than you uses your iPhone, you might not want the other person to peek at your favorites/recently contacted people. The other con is pictures: if you don't have proper contact pictures setup for your favorites/recent, it makes for an ugly interface in the switcher.