I am using IBM's speech-to-text service and it says active. How do I deactivate it so I don't use all of my minutes? I have looked everywhere and cant find a way to deactivate it.
If you don't invoke the API you won't be using any minutes. Provided you have kept your API credentials private, no-one else should be able to consume your minutes.
If you do want to deactivate the service, you can delete your service instance from your resource list. This will, however, also remove any language customisations that you have created.
As an alternative you can delete your API key. That way your customisations remain, but no-one can use the service.