»Click here to display Table of Contents« User Security > Working with Roles:
To delete a role from the list, either click on the role name and then choose Delete, or, from the main role list, click on the Delete icon on the far right. When prompted, confirm that you wish to delete the role. The role is removed from the list.
Help URL: http://www.yourdomain.com/help/index.html?usersecurity_deleterole.htm