To add a section or subsection, use the <sec> toolbar item to insert a section or subsection. The new section will appear below the current one.
To remove a section, select it and press <delete>.
You can also use the annotum source editor to precisely edit the article content. To do that, open an article and click the 'anno source editor' button:
Then use the editor to carefully remove the sections you want to delete:
Click validate, then insert to return to the editor.