|Yes, but possibly no-one who's an expert on web design, especially as you've posted in the 'Networking' forum, rather than 'Web Development'.|
I'm not an expert on it either, but I do know that PHP is often used to run other things in the background whereas HTML is 'front-end only', so if you do convert from one to the other you may lose functionality. Having said that you could try just changing the suffix from php to htm and see what happens. Alternatively open the php file in whatever editor you use and then resave it as HTML. Essentially you need to know what functions php was used for before you can decide whether converting to HTML will work.
"I've always been mad, I know I've been mad, like the most of us..." Pink Floyd