When you want to sell your mac or prepare it for a new user in the family, you can follow the next steps.
this step is optional and not needed if you already have everything backed up on the cloud or on a time machine.
De-authorize your iTunes account.
Sign out of your services:
Reboot your mac in recovery mode by pressing
command + r. Select diskutility and format your disk. As security option, I would always recommend the most slow but secure option…