Hello and welcome to both Nisus Writer Express and the nisus.com forums! I received your private email to us as well, but I'll reply with public answers here for the benefit of other users who may have similar questions.
To answer your first question directly: yes it is possible to create headings that do not have list numbering. That's entirely up to you and your document's stylesheet. In looking at the document you emailed us, the first heading has a manually applied list style. That's another way of saying the text was formatted directly by the user to add a list; it's not a paragraph style enforcing the list style.
Here's how you can remove the unwanted list style:
1. Place the insertion point (aka caret) anywhere inside the heading text.
2. Use the menu Format > Lists > Use None
After that the list numbering should disappear. Instead of using the Lists main menu you could also use the Lists toolbar item or Lists palette. You might find those to be more convenient as you get comfortable with Nisus Writer. Either way, just set the list style to "none" to remove the numbering.
In your email you also asked us about the second heading in your document. It appears much like the first heading in your file, but it doesn't actually use a proper heading paragraph style. Actually neither of your heading paragraphs use heading styles. Instead the text has been formatted directly using manually applied formatting like "bold". That's fine too if you prefer to work with manual formatting, but styles are more convenient, especially as a document grows in size.
To use a proper paragraph style you'll want to use main menus like Format > Paragraph Style > Heading 1
. Nisus Writer also has palettes that let you add or remove styles from your text. You should see the Character Styles and Paragraph Styles palettes in the default Writing palette group. That's the group in the palette dock with the little "A" icon at the top. The Lists palette is in the Paragraph palette group, with the "¶" icon at the top.
For more on using styles in Nisus Writer Express you might see the style section of the user guide
. The user guide is also available as a PDF from within Nisus Writer. Just use the menu Help > Nisus Writer User Guide
I hope this helps. Please let us know if you still have questions.