This article describes how to remove an email account from the Android mail application.
1. Click Home button.
2. Click Settings
3. Click Accounts & Sync
4. Click on account to be removed (in Managed Accounts section).
5. There will be a button down the bottom Remove Account.
6. Confirm that it's ok to remove the account and all emails, contacts and calendar items associated with it from the phone.
7. The account will now be removed.