To safely destroy data we can use the following command:

shred fichero

Where file is the file you want to destroy. This command does not delete the file but it writes random data on it. By default the data overwrites with garbage 25 times what is more than enough to cover the most demanding safety standards. This tool is very powerful and can destroy entire disks if instead of giving a file as an argument we give the path of a device such as "/ dev / sda"