How do I control devices that register that has been stolen
You cannot control them. All you can do is unlink them from your account. If someone broke into your home and stole your Roku then call the police.
Thanks for reaching out to the Roku community!
If your Roku streaming player or Roku TV™ has been lost or you suspect it has been stolen, we do recommend taking the following precautions. in this link What to do if your Roku® streaming device is lost or stolen | Official Roku Support
Hope you'll find this info useful. Let us know in case you've still got any questions.Best regards,Mary