|Well, yes it sounds like you just want to delete the PHP files. |
You know - you don't need to rename the HTML w/ a .HTML extension. An HTML-only file will work just the same w/ a .PHP extension - & this has the added advantage that you wouldn't need to update any of your links - so no broken pages / bookmarks / search engine links.
The mod_rewrite rule is probably just doing the same thing?? mod_rewrite is used to rewrite the URL request internally, so you could i.e., have your files with .html & have them automatically re-written when they came in with a .php extenion, i.e.:
RewriteRule ^(.*).php$ $1.html [L]
Would make it so http://www.example.com/test.php is served from test.html ... (but why not just replace the PHP files w/ the HTML versions, but leave the PHP extension ? )
You might also just look through the PHP files - a good programmer will put common files (header, footer, navigational stuff) in an include, so you don't need to update every file on the site when making a simple navigation text change. (Maybe take out all the dynamicness, but leave the <? include() ?> 's )