Spent a bit of time on this. After reading quite a few topics, checking out the demo at bepsays.com and trying out several things.
This is by far the simplest way to create a Nested Sections menu without the regular pages permalinks.
{{ range .Sections }} <a href="{{ .Permalink }}">{{ .Title | upper }}</a> {{end}}
If you have an even better way of doing this please share.
EDIT
The above menu renders only on the Main Section list and not on the Nested Sections list pages.
Now here is how to make a Nested Sections Menu appear everywhere within a Section.
{{ range (.Site.GetPage "section" .Section).Sections }} <li><a href="{{ .Permalink }}">{{ .Title | upper }}</a></li> {{end}}
EDIT
The above stopped working in Hugo 0.45 after the revision of the .GetPage
API.
But with the help of @kaushalmodi in Panic Error with .GetPage in Hugo 0.45 - #2 by kaushalmodi here is the revised code snippet to have this functionality in Hugo 0.45.
{{ with .Site.GetPage (printf "/%s" .Section) }}
{{ $sections := .Sections }}
{{ range where $sections }}
<li><a href="{{ .Permalink }}">{{ .Title }}</a></li>
{{ end }}
{{end}}