It's linked from The Register article but if you want to disable all the phoning home guff you need to add a file, config.properties into the site directory on your controller. If you only have 1 site then the probably directory to put that file on a Linux box is /var/lib/unifi/sites/default. Create a file called config.properties and add this line:
Code:
config.system_cfg.1=system.analytics.anonymous=disabled
Save and set the ownership to unifi:unifi. Restart the controller (possibly not necessary but can't do any harm) then force each device to provision.
You could also block the Unifi kit from being allowed access to the internet. It's the kit itself that uploads the data, not the controller. I'd already denied my kit internet access some time ago but I did specifically allow 123/udp out.
Yet another option is to block the domain trace.svc.ui.com in DNS. Pi-Hole makes that nice and easy.
It's all stuff that shouldn't be necessary. There should be a bit OFF toggle in the controller that disables everything, not just the PII stuff.