Um, not sure what you mean, Kittygal. Can you think of another way to phrase your question? Do you mean: restore them to an unused condition?
LOL OK. It sounds drastic. Open My Documents Open EA Games Open The Sims 2 Open Neighborhoods Delete the folders: N001 = Pleasantview N002 = Strangetown N003 = Veronaville (actually I'm sure about that order ) If you want to totally reset the game just delete the whole The Sims 2 folder in My Documents\EA Games\ but that will also delete all the sims and houses you might have made plus any custom content you have made or downloaded. After doing this, the next time you start the game it may take a little longer than usual to start up because the game will be busy remaking the missing neighborhoods in their original starting condition.