How to securely delete a computer file
When files are deleted from a computer, they are not erased permanently. There are two ways you can delete files from a computer so they cannot be recovered.
Delete the file using a third-party software program
Third-party programs provide an option to securely and permanently delete a file. When files are deleted, the space they occupied is overwritten with random data. Some software overwrites the hard drive space once while others overwrite multiple times. Some programs also including the ability to utilize the U.S. DoD 5220.22-M standard, which overwrites three to seven times or the Gutmann method that overwrite 35 times.
Examples of third-party software:
- Eraser - Free and open source Windows program.
- Freeraser - Free Windows program.
- DP Shredder - Free Windows program.
- File Shredder - Free Windows program.
- SDelete - Free Windows command line command to safely delete files.
Delete all files on the hard drive
If you are planning on completely erasing the data on your hard drive, some manufacturers provide free software for their products that performs a process called zero-filling. This type of hard drive erasure writes zeroes to the entire hard drive, effectively overwriting all files and folders on the hard drive. Essentially, all data is erased by zero filling the hard drive. You can do whatever you want with it after that point with no worries about someone stealing your files.
You can also purchase third-party software to securely wipe a hard drive of all files and folders. Similar to zero-filling, this software can write random data to the entire hard drive, effectively overwriting everything and making it impossible to recover any files.