How to Wipe Windows 7 on a Dell?

I think when you're talking about wiping Windows 7, you mean restoring it? If so, all you have to do is just restart the computer and at boot, when it shows the logo and some other information, simply push the f11 key. You should only have to do it once, and it should bring up the built-in recovery manager. Then, just follow the instructions that should come up and your Dell laptop will be completely restored.