Deleting Your Data Permanently
When you move a file to the recycle bin or trash and delete it permanently, the file is only inaccessible from the operating system. Anyone with the right forensic tools can still recover the file due to a magnetic trace left on the hard drive.
In order to erase data so that it is no longer recoverable, the data must be overwritten with ones and zeroes multiple times. To prevent the recovery of deleted files, you may need to use tools specifically designed to do just that. The program SDelete from Microsoft (for Vista and higher), claims to have the ability to remove sensitive files completely. Shred for Linux and Secure Empty Trash for Mac OSX are some tools that claim to provide a similar service.
The only way to be certain that data or files are not recoverable is to physically destroy the hard drive or storage device. It has been the folly of many criminals in thinking their files were impenetrable or irrecoverable.
Besides storing data on your local hard drives, your data may also be stored online in the cloud. Those copies will also need to be deleted. Take a moment to ask yourself, “Where do I save my data? Is it backed up somewhere? Is it encrypted? When you need to delete your data or get rid of a hard drive or computer, ask yourself, “Have I safeguarded the data to keep it from falling into the wrong hands?”