How do I reclaim a license key from a lost or stolen laptop?

We have about 70 users in our environment and we support Adobe Acrobat Standard 9, 10, 11, 12, and a hand full of Standard 17.   Two of our executives got their systems stolen, and we'd like to reclaim and reuse their Acrobat licenses on their new systems.

Question:  How do we get this done?

Thanks!

Leon