1. Backup Important Data: Before you proceed,
ensure you have a backup of any important data, as this process will
delete everything on the disk.
2. Restart Your Mac: Restart your Mac and hold
down
Command
(⌘) + R to boot into macOS Recovery mode.
3. Open Disk Utility: Once in Recovery mode, open
Disk Utility from
the macOS Utilities window.
4. Select the Disk: In
Disk Utility, select the disk
you want to erase from the list on the left.
5. Erase the Disk: Click the "
Erase" button.
Choose a Security Option:
In the Erase dialog, you can click on "Security Options"
to choose how securely you want to erase the data.
Move the slider to position >=3 to select
a security level. The higher the level, the more passes will be used to
overwrite the data (up to 7-pass erase for maximum security).
Erase: Click "
Erase" to start
the secure erasure process.