Activation lock lets you remotely wipe all the data on your iOS device. Here's how you can enable it on your iPhone, iPad or iPod.
1. Go to Settings.
2. Go to Privacy.
3. Go to Location Services.
4. Toggle the Find My iPhone switch to the on (green) position.
Once Find My iPhone is on, activation lock is enabled and you will be able to remotely lock or erase the data on your iOS device from iCloud.com.
Read more: Cult of Mac