Thanks for posting in the Roku Community!
We're sorry to hear about your friend, I understand that you want to know how to cancel the recurring charges and close the Roku account.
Please be noted that we do not manage or create/close Roku accounts for our customers for security reasons. In this case, we suggest that you contact the bank immediately to report the activity or for this specific inquiry. They will best be able to assist you further with that process.
If you need further assistance, feel free to contact Roku support at https://support.roku.com/contactus
Please let us know if there's anything else we can help you with.