The .NET IO unit has a two commands that should let you do the trick:
System.IO.Directory.GetDirectories("C:\\Program Files\\Your Directory\\*.*");
System.IO.Directory.GetFiles("C:\\Program Files\\Your Directory\\*.*");
I would write a method that takes the name of a directory and uses the "GetFiles" routine to get all of the files and to delete them using System.IO.File.Delete(path) in a foreach loop. Then, run a foreach loop on the result of the GetDirectories() command calling the function recursively.
Update: Steve Danner points out that the System.IO.Directory namespace has a Delete method so you don't need to go through the loops I talk about here. His answer is the right one and should be voted up. Mine, at this point, is more of a curiosity (although thank you to the person who gave me an upvote ;0).