Customize List—Does the same as the "Modify settings and columns" link
on WSS lists (see section "Basics of using and customizing WSS" of this
article). It allows you to add new columns, create new views, change
general list settings, and the like. You also can add, edit, or remove
Divisions or Regions. Under the Columns section, click the Division or
Region

Go to the sites  directory and select Customize List from the action bar. It’s just a regular SharePoint list so you can add/remove/edit choices to your hearts content.