To remove the navigation module from your landing pages, you'll will need to access the template the page is using to delete the menu module it contains.
- Navigate to Content > Landing Pages, locate the page in question and access it for editing.
- At the top of the editor click Settings > scroll down to Template Settings > click Edit Template. You will be alerted if this template is in use by other landing pages. If you want the edits to apply to other landing pages using the same template too, click on Edit this layout. If not, select Make a copy, so you can clone the template and ensure the edits you'll make only apply to this one landing page.
- You should now be looking at the template. Locate the Simple Menu OR Advanced Menu module on your template > click the Gear Icon on the module > select Delete module > click on Publish Changes on the template to push the changes live.