I'm not so sure that removing the dynamic menu is any way contradictory to the use of a CMS ... I have several sites where I have absolutely no need for the adverse performance impact of a dynamic menu (not to mention the server resources) and have done exactly what the poster is asking. Here's why:

1) Good information architecture discourages a large number of top-level choices. Once the high-level architecture of the site has been defined, it does not need to change too often and a dynamic  top level menu with fly-outs adds no value, and is in-fact detrimental. It's trivial to change it when the need arises.

2) Content Management Systems are for managing content...there is no pre-condition that is should be about managing pages in a page hierarchy. If I have my page hierarchy defined and all I want to do on my site is to manage content within the pages, that's a perfectly acceptable use-case.

3) An intelligent side menu is more versatile, visible, accessible, contextual and performant than a multi-level, dynamic top menu.

4) Admin/Host are being deprecated from the menu at some point in the future (this is why they were added as Control Panel links).

To answer the original question:

a) Locate your skin layout control...this will be in /Portals/_default/Skins/{Your Skin Name}/{Your Skin Layout Name}.ascx or /Portals/{Your Portal ID}/Skins/{Your Skin Name}/{Your Skin Layout Name}.ascx

b) Edit this file with Notepad or other text editor and delete the following:

<%@ Register TagPrefix="dnn" TagName="NAV" Src="~/Admin/Skins/Nav.ascx" %>

Why mot remove the DNNMenu add a Menupane and add a html module there.

Now you can change the menu ;)