Hi, there is Currently no way to remove that menu button, and honestly, I don't think there will/should be one, that small button is the Only portal and way for users to access their extensions and the rest of the options, without it, there will be so much confusions and lack of control/productivity.
@HotCakeX correct. We do not want to allow you to hide the ... menu for the reasons called out here as well as security information. When you click on ... > App Info you can see certificates for that URL and permissions for things like "Location". We must allow users easy access to those settings to avoid confusion and give people choice.