The Windows Assessment and Deployment Kit (Windows ADK) is a collection of tools that you can use to customize, assess, and deploy Windows operating systems to new computers.
Step 1 – Get your copy of ADK 8.1 – Here
Step 2 – Make sure you un-install your old ADK from your machine.
Step 3 – Once your old ADK v8 is removed double click on your installation file and start the installation
Step 4 – You leave the default or add any additional feature for your ADK 8.1. I normally like adding USMT