Basically you cannot until the old information has been overwritten by new info. All that happens when you delete a file in Windows is that the identifying header gets erased. This then means that whilst Windows will still look at the code but because the header isn't there anymore it gets passed over, that's one of the reasons a computer slows down over time . If new coding is allocated to that part of the disk then it will overwrite that old code. Even so, with the right software, some or all of the info can be retrieved. That's the way that file recovery software works. Software, such as CCleaner, use multiple overwrites in an attempt to wipe all the information from part or all of the HDD, up to 35 times in the case of CCleaner. If you are not bothered about that aspect of file deletion then what Darren has said will suffice.