Disk Utility: erase iMac 3TB Fusion Drive
The original HDD will be replaced by Apple and I want to Security Erase it before giving the iMac to the Apple Store.
Security Options, Format, Name are grayed out. After backing up the drive, how do I erase the original installed Fusion Drive?
TIA
iMac with Retina 5K display, OS X Yosemite (10.10.3)