Gracie Fetch

You will need access to the server for this. If the site is created using .NET there probably will not be any html files for you to edit. The files that generates the markup will be asp or aspx files. If you really own the site you should be able to access the server. Then You could use a text editor and try to search and replace for the menu title in any asp/aspx files, but it is most likely that the whole menu is generated by a function/class file which has been compiled to byte code when saved. The original code behind files might be on the server, in which case you can open them in Microsoft Visual Studio and edit/recompile them. But you will need server access for this. These files can not be downloaded through normal  http access. 
EDIT: You could of cause also download a a static copy of rhe generated HTML and edit it a wysiwig editor like dreamweaver. But you will lose any functionality that runs on the server.