There are two options to properly decommission a computer used to access or store private data: destroy or repurpose. You can destroy the hard disk yourself and evidence the process with pictures or hire a third-party who will provide a certificate of destruction. You can securely repurpose an encrypted disk by using the operating system feature to perform a low-level format.
Remember to record decommissioning with evidence in your cyber folder and remove the computer from your asset inventory list.
