Deleting data from a disk properly shouldn't be so difficult for a common user. To eliminate this data we need a process of writing all the sectors in a loop, to make the recovery of residual data an almost impossible task.
To remove data from a disk, it is recommended to use the DBAN tool (Darik Boot And Nuke) which can be executed from a CD or a pendrive.
Simply choose the disk or disks that you want to remove safely or opt for the standard method, without configurations, which offers high quality erase levels, and execute the action.
The standard method used by DBAN is the "DOD Short", designed by the US Department of Defense, which uses triple writing in each sector of the disk.
First, it uses a character, a complementary character and finally a random character, later it carries out a verification of the rewritten sector.
It is a slow process, but the result is reliable, because after completion, the data recovery process will be impossible and only accessible with "very advanced" methods.
This type of erase method does not physically damage the hard drive, so it can be reusable without problems, in fact reusing it will help to improve the elimination of the previous data.
If you have an SSD disk, they behave differently, which is why they require specialized methods and deeper tools, since the manufacturer is the one who knows exactly the methods used to record data in memory cells.
You can use the "ATA Secure Erase" process for this type of hard disks, since this powerful tool (SSD Guru) can be used from Windows or from the "DOS" boot, the process of this tool makes the discharge of electrons from all the hard drive's hardness, eliminating any information stored in them. It takes a few seconds to execute and the deletion effects are definitive.
Our advice is to find the right tool for the deletion of information with the manufacturer of your hard drive, almost all of them have this kind of useful tools and they are free.
So if you need to do the deletion of your hard drive without the help of an expert you can use some of these tools that we recommend.