Since ES6.3, it is impossible to install or uninstall x-pack. It's built-in to the default distribution.
So, how to set up the installation process in order to reject the "trial" license? Before we were able to set
xpack.license.self_generated.type: basic in elasticsearch.yml. But now, there's no elasticsearch.yml since X-pack is installed at the same time as Elasticsearch.
I can't find info on what we need to do anywhere.