The thing is you did not lock anything. Your employee did because you had no protocols in place to consider what happens when said employee leaves. Instead you should have them already pre-locked to your company.
Apple Deployment Programs- Upgrade account to access all programs
About Mobile Device Management
"This document offers guidance on some important considerations for getting the most out of your iOS deployment." Covers: Prepare your infrastructure. Set up devices. Configure and manage devices. Deploy apps and content. Plan for support.
Quick overview of zero-touch MDM enrollment, DEP.
Consider DEP, Device Enrollment Program. Use VPP, Volume Purchase Program. Select an MDM, Mobile Device Management. Read the Google doc below and nsdjoey write up.
IT Resources -- ios & OS X -- This is a fantastic web page. I like the education site over the business site.
View documentation, video tutorials, and web pages to help IT professionals develop and deploy education solutions.
Education
scroll down after all the pretty picture. Click on the words "For It".
Business site is:
If necessary, scroll down until you see the Browse IT Resources button. Click on button.
MDM -- Mobile Device Management
VPP -- Volume Purchase Program
Joe Rowe's Excellent guides:
IT managers who are new to configurator and managing a cart of ios devices:
[ original announcement ]
Quick help presentation for students: