If you want ultimate reassurance of destroying data, destroy the device with a hammer or drill through the drive with multiple holes. For extra security, use Blancco Mobile for the Android or iOS. For most recent smartphones, do a factory reset, but also remove the SIM card. For Windows PCs, use Active KillDisk or McAfee Shredder. To wipe a Mac, use WipeDrive or the OS X Disk Utility. Reformatting the hard drive can still leave data. No, not with a rag, but wipe out the data, completely. For Android or iOS, activate the Google Auto Backup service or Apple’s iCloud. If you want to sell a storage device, first back everything up on it with a flash drive, external drive or automated backup service.
