There is a secret menu that allows you to display a TEST message instead of an ad. Here is how to do it (advice copied from Reddit user Hookbeak):
“Doesn’t work on every roku but try this to remove ads:
Access secret menu 2 as follows:
Home home home home home up right down left up
Choose “cycle home screen ad banner server” and click ok until it changes to “staging 2”
Press Home to exit.
Ads are replaced with a nice blank box”
You can try different servers (besides "staging 2"), but that is the one that worked for me.
