You can create, edit, and delete email addresses from the Email Control Panel in your Yahoo! Small Business account.
How to manage email addresses from the Email Control Panel.

There are a few ways to reach your Email Control Panel:

Web Hosting customers:

Click the Email tab on your Web Hosting Control Panel.

Web Hosting Control Panel Email Tab.

All Business Email customers:

Sign in to your Business Control Panel and click the "Email Control Panel" link associated with your plan.

Business Control Panel Email Control Panel Link

OR

Start from your Web mail interface:

1. Sign in to your account at http://mail.yourdomain.com/

   Note: Be sure to replace "yourdomain.com" with your domain name. You'll be prompted to enter your Yahoo! ID and password if you haven't already.

2. You should automatically be taken to your Business Mail account. If you are not:
   • Locate the welcome message in the upper-right corner of the screen, e.g. "Hi, Mary", and click the name or the image beside the welcome message.

     
     Business Email Welcome Message.

   • Select your Business Mail account from the list of available addresses.

     
     Welcome Menu: Address List

   If you're using the original version of Business Email, Classic interface, your available email accounts are listed on the left side of the screen. Select your Business Email account from this list.
3. From the main Yahoo! Business Mail page, click the Tools (gear) icon link in the upper-right corner of the page.
   
   Business Email Tools (Gear) Icon
4. Select "Mail Options" from the pull-down menu.
   
   Business Email Tools Pull-Down: Mail Options
5. Click the "Administration" link located in the left column.

   
   Mail Options Menu: Administration

6. Click the "Manage" link under "Manage Business Email".

   
   Business Email Administration: Manage Link

7. The Email Control Panel will open in a new window, where you can add email users, check your email, and more.