Somewhere along the line I create a bo called BoUsers then renamed to to boUsers. See attached. Both still show in the mapper and there is no way to get rid of BoUsers?

Each time you go into the BusinessObject Mapper, it re-scans the project, so you have some remnant of the BoUsers name within your project.  Most likely, when you renamed the BoUsers to boUsers, the project couldn't compile so it did not rename all uses of the BoUsers name.  Check the boUsers.cs file and the boUsers.Designer.cs file.  Most likely, the "partial public class BoUsers" at the top of the boUsers.designer.cs file did not get renamed properly, so check the designer file first.