Any subscriptions you've obtained through other services (Hulu, Prime Video, etc) will have to be unsubscribed through those services.
Any subscriptions obtained directly from the channel will have to be unsubscribed on the channel's website.
Note that with most (all?) subscriptions you pre-pay (or obtain a temporary free trial for) for a defined subscription period which then auto-renew when the subscription (or trial) periods expire. When you unsubscribe it stops the auto-renewal but the current subscription stays active until the prepaid subscription period runs out. Few, if any, will cancel immediately and refund the unused portion of your prepaid subscription. This is all explained in the conditions you agree to when you subscribe (you know, all that stuff we all agree to without actually reading it).
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