You should be able to cancel any subscriptions you obtained via Roku via your account at my.roku.com. Any subscriptions obtained directly with the channel will have to be canceled directly with the channel. You should be able to tell which is which by seeing who is charging your credit card for each subscription.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T