How do I delete the email address that Veriozon Wireless rep paired with my Droid and replace it with a different address?
The easiest way would be to go to menu>settings>accounts & sync, select the account (I'm assuming you're referring to your gmail account, so select google), then press the remove account button at the bottom. You may lose all your contacts and other data associated with your google account, possibly even your apps, so be aware of this beforehand. You can then add the new account from the accounts & sync menu.
If you are willing to completely start over with your phone, another alternative would be to factory reset it (menu>settings>privacy>factory data reset). This will return your phone to an out-of-the-box condition, and you can use a different gmail address if you like.