I don't think there's any way to delete the data, but unlinking it from your account might accomplish the same thing. Go to https://my.roku.com/account and unlink it and you probably also want to manage any subscriptions you may have. I don't know what would happen with something like a Netflix account managed through them.
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution." If you appreciate my answer, maybe give me a Kudo.