Computer Hard Drives: The method used to erase data off of a hard drive before giving the computer away depends on the information you want to preserve. Your options are:
If you are giving the computer to someone else, you may not want to eliminate all the valuable software along with your private information. However, just deleting your personal files does not make them unrecoverable. To completely destroy a file, you must use a data-shredding program. It takes a conventional “erase” a step further by actually writing over the file.
Completely reformatting your drive may seem like a good option, but this method doesn’t eliminate data either — the information can easily be restored using off-the-shelf data recovery software. Many of the best data erasing programs come from the same companies that produce data recovery software. Set aside some time: This can take hours on large hard drives.
There is no better way to completely annihilate your data than to physically destroy the device that stores it. We still suggest a software shredder first, but if your personal data security justifies the extra effort, put on protective eyewear and gloves and break out the power tools. Drilling four holes through the platters will ensure that they never spin properly again. Better yet, unscrew and remove the top lid of the drive, and go at the platters with a sander or angle grinder. Scuff the surface of the platters until all the shine is gone.
Flash Drives: Flash drives are different than hard drives. It has been found that various methods to wipe data off of a flash drive are unreliable. I recommend taking a hammer to the drive. You want to make sure you smash the circuit board and chips.
Cell Phones: Modern cell phones are like computers; deleting data using menus may not truly delete it from the hardware. Always wipe your phone by deleting the data using menu settings and then performing a factory reset. Every phone has a different process, so check the phone’s manual to restore the phone to its factory settings, or search YouTube for an instructional video. According to PCWorld, no wipe solution is perfect. The only way to totally guarantee old cell phone data is gone for good is to take the phone apart and physically destroy the memory chip.
After making sure all sensitive information is wiped from the device, you may want to consider giving it to a local non-profit organization. Although, be aware that many organizations have become more selective about what devices they will accept.
Check with your local city or county. Many have computer recycling programs.
Following are some additional resources: