3. Work with disk units
3. Work with disk unit recovery
Select option 5. Delete disk unit data or you can select option 2. Disk unit problem recovery procedures, then 1. Initialize and format disk unit
Here is the IBM way. Everything will be erased.
Initialize Disk Drives so All Data is Erased Off of a System
You might also want to save the license keys first just in case you’re going to reuse the box.