Click on the Manage / Add / Remove accounts link in the Mail Menu area.
Click on the 
button next to the unwanted email address.
Your account has now been deleted.
You can delete an email account when the account is no longer needed. You can not delete your default account.
Warning: Make sure you download any mail that you want to keep, as deleting the account will delete all of the mail still in that account. You can not recover this information once the account has been deleted.
To delete an email account:
Click on the Manage / Add / Remove accounts link in the Mail Menu area.
Click on the button next to the unwanted email address.
Your account has now been deleted.
EmailAccounts Home
Reading an email account
Configuring Outlook Express to read email
Using the Webmail
Changing an email account password