I'm not sure what version of windows you're using, but yes you're going to want to format your drive (aka deleting any info on drive).

Try having a look at the following website, it gives info for all sorts of windows installs, from fresh installs to needing to format etc.    If it's not clear enoguh or you need more info, come back and let us know.  (Sometimes deleting and creating partitions can be a lil tricky, you'd preferably like to not delete the diagnostic partition)

www.windowsreinstall.com

Alternative to all that, if you got your system within the past 6mo you may have an image restore located on a hidden partition that will do this whole job for you in about 10 minutes, vs 2h for reinstalling windows and drivers.

Feel free to call tech support and have them walk you thru, they'll also help you to install all the drivers in the correct order and what not.

If you didnot repartition the drive, you can reset everything to fatory specs. You can do this at the Dell splash screen by pressing CTRL+F11. You will lose all files. To retrieve them, use a Notebook to IDE adapter and put it in a desktop as a secondary drive and do a drive to drive copy of your files.

Other than that, no. THese are the only 2 ways to do it. Sorry.