I have had to do this a bagillion times with different sites and have found a decent way that works for me. Consider the following:
... more random content...
What I do to remove the div called "removeDiv" in this case, is highlight everything from the </div> of the div "someDiv" all the way through the opening of the "footer" div. Now paste that into your find window.
in the replace window, simply replace it with the </div> from "someDiv" and the opening of "footer" div with no space inbetween.
Choose replace all and make sure in the options of the find and replace are set to "source code" and entire current local site" and you should get something like:
</div> <!-- from the "someDiv" -->
This works for me in dreamweaver CS4 and has worked great for the most part since Dreamweaver 8.
hope this helps.