You can't change the IR code set each responds to, but what you can do is switch your Roku tv to wifi Voice remote. Once paired it will only control the Roku tv. You can purchase one at walmart for $19.88 or for rechargeable Voice pro $29.88. Then abandon the Roku IR remote for good.
Edmund
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee.