Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
What are you watching that has these ads? Unless it's The Roku Channel, Roku themselves have no control over it. The only way to get ad-free viewing is to have a paid subscription to a provider such as Netflix or Prime Video (and they even have some ad supported content, but most is ad-free).
I agree with @boogernose , for free content you're going to get ads. Depending on the service provider, even paying something might only reduce the ads, not eliminate them completely.
Dan Ultra (4640), Ultra (4670), Ultra (4800), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.
I guess we all have different tolerances for ads. Several people I know have not watched any ads for decades. Others will put up with anything for "free TV". I'm closer to the former. I used to watch more youtube but even in the past I was annoyed at how long it took many youtube videos to "get to the point". Since ads have gotten more common on youtube, I go there much less. In standard Econ 101 they teach a demand curve of price vs demand, but for me there's a demand curve of ads vs demand too. But as my demand goes down, they are hoping to make more money on the people still willing to watch.