The idea behind a separate topic is not to hide anything, but to keep the topic focused on your concerns so it does not get buried in all the postings here.
You can currently opt out by not using the UPC to login. You do not have to sign in to use Unraid. It is not a requirement. I too share your concerns about cloud storage, that's why I use Unraid to store all my stuff. I don't put anything on the cloud.
Removing the UPC is a quick 'elegant' solution to you. I get that. But, one of the concerns with your proposal to remove the UPC from the webGUI is that it is used for other purposes that is not tracking users in any way, For example to request a new license if your flash fails, or to allow secure remote access. If it is 'hidden' or enabled by a setting, it becomes cumbersome to a user to figure out how to enable and use it for things like requesting a license replacement.
All that being said, if you'll start a new topic, we can discuss this further and give Limetech some ideas and the time to decide the best way to address your concerns and the valid concerns of those that choose to use the UPC.