So connect the device to your computer via USB and delete or remove internal ... levels of secure erasing and select which drives you want to erase, if the computer has more than one.
Click Erase Volume Group (or Erase if that button isn't shown) to wipe the drive. (Credit: Apple) Go to Disk Utility > Quit Disk Utility to exit the Disk Utility window and go back to the Recovery ...
One popular way of avoiding this is backing data up through a USB or another external hard drive, but even that comes with its own problems, such as risks of data loss. That's why we recommend ...