Install once more GOG Galaxy and then install again steam plugin in GOG Galaxy. After that remove plugin connection from library and at the end uninstall plugin. You will have clean GOG library without steam games. I have done this twice in past years and it works.
Install once more GOG Galaxy and then install again steam plugin in GOG Galaxy. After that remove plugin connection from library and at the end uninstall plugin. You will have clean GOG library without steam games. I have done this twice in past years and it works.