Hi @Joe6 
As @Andrea_Mayer wrote: I was able to delete the last section once I moved the tasks out of the section.
If the section contains tasks and you try to delete it, then you have the option to either delete the tasks as well or move them to another section. So,try creating a new section before deleting it.
Also, I don’t think you can have a ‘no sections’ empty project. There should be at least one section. Please, anyone… feel free to correct me if I’m wrong! 
Hope that helps.
Elina.