Formatting a hard drive is the best way to erase all the information on a drive and is also something you must do to a new hard drive before Windows 7 will let you store information on it. It might seem complicated - granted, formatting a drive isn't something anyone does very often - but Windows 7 makes it really easy.
This tutorial will walk you through the entire process of formatting a hard drive in Windows that you've already been using. You can also use this tutorial to format a brand new hard drive that you've just installed but that scenario requires an additional step which I'll call out when we get to that point.
Note: I created this step by step tutorial in addition to my original how-to called How To Format a Hard Drive in Windows 7. If you've formatted drives before and don't need all this detail, those instructions will probably do you fine. Otherwise, this tutorial should clear up any confusion you might have had reading through those more summarized instructions.
The time it takes to format a hard drive in Windows 7 depends almost entirely on the size of the hard drive you're formatting. A small drive may take only several seconds while a very large drive could take an hour or so.
The first thing you need to do is open Disk Management, the tool that's used to manage drives in Windows. The fastest way to open Disk Management is to click on the Start button and then type diskmgmt.msc in the search box directly to the left of the Shut down button. Hit your Enter key or click on the diskmgmt entry that shows up in the search results.