Just as we tend to keep the outside and inside of the computer as clean and dust free as possible, we must also try to clean the space in the hard disk to make it free of any data that has already been deleted. So a cleaning process is always necessary for a computer.  The process or cleaning or for wiping the personal data is quite trouble free and uncomplicated.   To wipe off all the   data completely you need to write over the existing data. By re formatting the drive or by deleting all the files your hard drive is not wiped off the old data. To help you in the wiping process there are a number of software that can be installed and are programmed to wipe the drive. These wipes are also known as shedders and with a random configuration of zeroes they are able to wipe the data and ready to install new data. These wipes are highly user friendly and quite affordable. It is sometimes recommended by experts that to wipe data from hard drive, you need to overwrite on the drive for more than seven times to really ensure that the drive has been completely wiped off, of its old data and now there are software available for the same to help you do the overwriting.