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Wednesday, November 11, 2020

How to Erase Sensitive Data from a Laptop, Tablet or Smartphone

 By Catherine Powell

Many consumers are thrilled when it comes time to purchase a new computer or smartphone.  With Christmas only a month and a half away, people will be purchasing new laptops, tablets and smartphones.  New devices are faster and have more features than older models.  The problem is, how do you donate or sell the older device when it potentially contains everything from personal contacts and photos to bank account numbers and your social security number?  While you can delete all of the above mentioned files, that doesn’t necessarily mean that the files have been permanently eliminated from memory.  In fact, there are inexpensive software programs on the market that can recover deleted files from any device.  Other than burying your unwanted devices in the backyard, what can consumers do to steam clean all of them?

Why aren’t deleted files really deleted? – One of the biggest misconceptions in computing is that by hitting delete and then emptying your computer’s recycle bin, you have erased a file from your device.  This couldn’t be further from the truth. All you’ve actually done is erased the information that points to the file.  Operating systems use pointers to build a directory that computer users use as a directory.  Just as eliminating a page from the table of contents in a book doesn’t eliminate the page, neither does erasing a directory entry remove the data from a hard drive.  It’s still on the hard drive until the file is overwritten, which may or may not occur unless you use software designed to do just that. 

How can you recover files that have been deleted? – If you’ve ever accidentally erased a file from your computer, you probably thought it was lost forever.  If you haven’t emptied your recycle bin, recovering it could be as easy as clicking on recycle, right clicking the file and clicking “Restore File”.  Once you empty the recycle bin, recovering the deleted file is a little trickier, but far from impossible.  If you have a backup of your hard drive, the easiest way to recover the file is to transfer it from your backup drive.  If you haven’t backed up the file, the easiest way to recover it is to download a file recovery tool like Recuva that’s designed to find and restore lost files that were erased from your computer.  Provided that the file hasn’t been overwritten, Recuva can usually recover the deleted file in short order.  That means the sooner you use a data recovery tool, the better your chances of recovering a file that was accidentally erased.

How can you erase sensitive data from your computer? – Depending on the age and type of computer you own, overwriting sensitive information or the contents of the entire hard drive can be as simple as point and click.  While you may have to purchase a software package like Eraser or File Shredder, if you have a Windows computer, you may already have the tool you need to get the job done.  If you have a Windows 10 device, Microsoftoffers a tool called SDelete that is free to download and use. 

SDelete is a command line utility that takes a number of options. In any given use, it allows you to delete one or more files and/or directories, or to cleanse the free space on a logical disk. Securely deleting a file that has no special attributes is relatively straight-forward: the secure delete program simply overwrites the file with the secure delete pattern. What is more tricky is securely deleting Windows NT/2K compressed, encrypted and sparse files, and securely cleansing disk free spaces.” 

Some versions of Windows have a built-in tool called Cipher that can be used to either encrypt and decrypt sensitive information as well as overwriting deleted files.  The only proviso is that Cipher will not overwrite files that are smaller than 1 kb.  Below are Microsoft’s instructions on how to use Cipher to overwrite files: 

1.    Quit all programs.

2.    Click Start, click Run, type cmd, and then press ENTER.

3.    Type cipher /w:folder, and then press ENTER, where folder is any folder in the volume that you want to clean. For example, the cipher /w:c:\test command causes all deallocated space on drive C to be overwritten. If C:\folder is a Mount Point or points to a folder on another volume, all deallocated space on that volume will be cleaned.

How can you delete sensitive data from an Android device – If you own an Android tablet or smartphone, there are several things you need to do before you sell, trade, give away or deep six your device:

1.      Make sure your device was encrypted at the factory.  Most are, but if your device is more than a few years old, it might not be encrypted.  The way to check this is to access the System Settings tab, followed by the Security tab.  Under Security there should be a listing with the title Encryption.  If you can’t find it, don’t panic.  Simply use the search function in the Settings tab to enter “encrypt”.  All you’re trying to do is verify that your device was set to encrypt all entries at the factory.  If you discover that your device isn’t encrypted, you can toggle the button on the Encryption tab to have the device encrypted after the fact.  (Note: This could take an hour or more.)  If you still can’t determine if your device is encrypted, it’s best to contact the manufacturer to find out if your device is encrypted or how to encrypt it.

2.      Remove your SIM card and any other external data storage card like an SD card.  If your device has a virtual SIM card, don’t panic.  Simply move onto the next step in the process.

3.      Perform a reset by going back to settings and looking for “Backup & Reset” or simply “Reset”.  On some Android devices, this function is located on the “Advanced” tab.  Select the factory reset function and any options related to erasing data and/or accounts.  Once you reach the confirmation screen, the system will prompt you for your PIN, password or pattern for verification.  Once you do this, you can expect it to take some time for the operating system to do its thing.

4.      Eliminate any account associations. Don’t forget to remove your device from your Google accounts, as well as any other accounts associated with it.

How can you delete sensitive data from Apple devices? – Needless to say, if you own an iMac, iPad or iPhone, you too would like to know how to completely erase sensitive data from your devices.  Below are several links to related articles:

1.      What to do beforeyou sell, give away or trade-in your iMac 

2.      How to wipe all personal data and erase your iPhone & iPad 

Catherine Powell is the owner of A Plus All Florida, Insurance in Orange Park, Florida.  To find out more ways to save on flood insurance, check out her website at


  1. The Christmas holiday is also a field day for cyber-criminals. Make sure you don't fall for any clickbait.

  2. Having been an IT manager for many year, I know the importance of wiping the sensative data off equipment when it time to retire or sell that equipment off. These tips are right on the money for anyone who reads the article.


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