Hi Ian,
We could remove the text with steps below:
1. Navigate to Advanced Settings > Customizations > Entities > Marketing page configuration > Business Rules
2. Deactiviate "Set banner required fields" rule.

3. Create a Marketing page configurations record in new Settings(in sitemap) > Marketing settings > Landing pages,
we'll find the Privacy banner text is no longer business required.(with other two privacy fields.)
So just add privacy link and URL, then set the new configuration as default.

(We could also edit the default existing configuration.)
(It may take some time to refresh data and cache, you could restart portal if setting not works immediately or wait for several minutes.
For me, I created a new configuration as default and a new marketing page record for test without restarting.)
Result:

Regards,
Clofly