Q: How to lock out a stolen iPhone 6

Go to iCloud.com on a computer, or to the Find My iPhone app on another iOS device and sign in with the same Apple/iCloud ID that you have signed in to your Lost iOS devcie. Click on the Find My iPhone app, and select your device, then click on Lost Mode to put a Lock Screen passcode on it.

Best of luck,

GB

Hi,

Report a lost or stolen Apple product

Learn what you can do about your lost or stolen iPhone, iPad, iPod touch, or Mac.

If you have lost or found an Apple product, please contact your local law enforcement agency to report it.

You can take steps to find your lost or stolen iPhone, iPad, iPod touch, or Mac if you've enabled Find My Mac and Find My iPhone apps. Using your Find My apps allows you to put your missing device in Lost Mode, see its location, or erase its data. Other than the Find My iPhone and Find My Mac apps, there is no other Apple service that finds, tracks, or otherwise flags your device for you.

Learn how to locate Apple product serial numbers.

Above information also available here >  Report a lost or stolen Apple product