InfinityFree does not use server-side caching, there is no cache to clear. I’m not sure I understand the problem that you are having, can you share code samples and the error message you receive?
Also, please type in english or use an online translator before posting, thank you!
I had a look at both files at the website and the pages I see match the code that should generate them. The index.php redirects to the default.php page, which is mostly just HTML code that is shown as-is in the browser. The file accueil.php also is mostly HTML that is also being shown as-is.
You say it’s an OPCache issue, so I’m guessing that what you see on your website doesn’t match what’s defined in your code. Can you please point out what exactly is different between your code and what you see?
And just for the record: we do have OPCache setup, but it should be setup in such a way that any change in code is applied basically instantly. I would like to verify that there is actually an OPCache issue before tinkering with server settings that may not have any effect.