If you are selling your old computer or giving it away for charity, you should first remove all of your personal data from its hard drive. Deleting file is not enough since they can be recovered easily using freeware tools like Recuva. The best thing you can do to ensure that none of your personal files end up in the wrong hands, is to secure wipe the entire hard drive and then re-install the operating system, driver software and other third party software. This way all of your personal files will be completely erased and the computer will work like brand new.
You can quickly erase your hard drives or the individual partitions on it using free MiniTool Drive Wipe software. Drive Wipe shows a user interface from where you can choose to wipe a partition or wipe a disk. For the partition wiping, you have to pick a partition from the available drives on your computer. For the disk wiping, you have to pick one of the hard drives attached to your computer. If you choose the disk on which Windows is installed or the system partition on which Windows is installed, it will continue at the next boot and complete the wiping process. It is not recommended to use MiniTool Drive Wipe on solid state drives (SSD) as it will only reduce the life of the SSD.
For secure wiping a partition or the entire hard disk drive, you have to pick one of the secure erase methods. There are five secure wiping methods available – fill sectors with 0, fill sectors with 1, fill sectors with both 0 and 1, US DoD 3-passes and US DoD 7-passes. For majority of the users, the simple fill sectors with 0 method works well and is quite fast. If you proceed, it will start the wiping all of the data including the free sectors. There is no turning back at this stage. Depending on the hard drive capacity, it may take many hours for the drive wipe to finish erasing all the data.
You can download MiniTool Drive Wipe tool from https://www.minitool.com/free-tools/minitool-drivewipe.html.