It looks like there's no way to disable the cookie handling per se but this seems to work: Create your own HttpClient, then use HttpClient.doOnRequest to register a callback to be called before sending the request. In the callback, call HttpClientRequest.requestHeaders() to retrieve the request headers, then delete the Cookie header.

Sample code that removes User-Agent header before sending the request.

public class Main {
    public static void main(String[] args) {
        HttpClient httpClient = HttpClient.create().doOnRequest((request, connection) -> {
           request.requestHeaders().remove("User-Agent");
        });
        WebClient client = WebClient.builder()
                .clientConnector(new ReactorClientHttpConnector(httpClient))
                .build();
        Mono<String> r = client.get().uri("https://www.google.com").retrieve()
                .bodyToMono(String.class);
        System.out.println(r.block());
    }
}

In my testing, I'm not seeing that Reactor Netty HttpClient is doing anything at all with the cookies that come back in the response. I was actually looking to enable a cookie store like the Apache HttpClient supports, but to all indications the Netty HttpClient has no such feature.

In the entire codebase of Reactor Netty, there is no usage of the "set-cookie" header except in one of their unit tests. This tells me cookies are ignored by default unless the client code chooses to look for them.