How to Disable control of my TV in Roku Ultra remote?

Check box in Settings next to "IR" is always there, cannot remove it.
Why I care: my Roku Ultra says in remote section: "set up your Roku voice remote to control the power and volume for your TV"

It's handy to control Volume BUT it's very bad that I will have this option ONLY if at the same time my TV power goes OFF when I press power button on my remote (by the way, does it turn Roku Ultea power off or just TV?) 😞
Is it possible to leave TV Volume control BUT do not have remote's Power button to turn TV off?
I usually have other stuff on other HDMI inputs of my TV and it's very bad that all of them are gone when I press Roku power button!