I think the title is self-explanatory. E.g. this method would be useful if it existed: ``` php \Symfony\Component\BrowserKit\Client::unsetServerParameter($key) ``` The request is different if I use `setServerParameter($key, null)`, so not the same thing. See [this Stack Overflow answer](http://stackoverflow.com/a/40258231/1903743) for a use case.