I have exactly the same problem. Godaddy installed WordPress 5.0 automatically, my site broke. It removed the capability to assign parents to pages. I contacted the support to figure out how to downgrade Word Press Core. They told me to restore the backup from the day before UP Core update. Since I hadn’t touched my site since the release day, I was able to roll back to WP 4.9.8.
I would like to stop my site to update automatically to WP5.0, I found this plugin. It would be a wonderful thing if it works, but the plugin doesn’t let me change the setting. When I press “Disable All Updates”, it doesn’t change the green button. I can’t change WordPress core update.
I would really don’t want Godaddy to update WordPress Core. Is there a way to solve this?