How can I delete the data on my hard drive?
From time to time it may be necessary to erase the data on your hard drive. It might be that you are selling the machine, passing it to another user, or just want a clean installation.
Even if you were to reformat the hard drive and reload the operating system, the data is still stored (although it is not easily accessible). Deleting files and then emptying the recycling bin does not delete the data either. The physical space where the files are stored needs to be overwritten with data several times over to ensure that the data cannot be recovered.
To wipe an entire drive
A useful free tool to do this is Copywipe
Boot Copywipe from a CD and you to erase the entire content of a drive by overwriting it.
To wipe a drive or a partition
Another useful tool is Killdisk
KillDisk for Windows will allow you to erase drives and partitions from within the Windows environment which is useful for erasing flash drives external drives or partitions on your hard drive.