From the business side of the story, stopping recurring billing is usually as easy as finding the billing process and clicking on “Stop.” When you’re a customer, it’s not always that simple: you’ll have to find the permissions you’ve given the merchant and stop them, depending on where you are in the billing cycle at that point, as some will still charge you for the next invoice if your cancellation comes in too late.
It’s best to consult the fine print of your agreement for clarity. If this method for stopping the process doesn’t work, the second-best thing is contacting the merchant: their customer support often has ways of shutting it down, including manual overrides, often included in the software they use.