### Answer
Currently, the documentation does not provide specific instructions on how to cancel a subscription directly through the Vapi billing portal. For assistance with subscription cancellation, it's recommended to contact Vapi's support directly to guide you through the process. This ensures that your request is handled properly and all your concerns are addressed.
For more information on billing or to contact support, you may refer to the billing documentation or the support links provided in the Vapi documentation. Unfortunately, without direct instructions in the provided sources, reaching out to support is the best course of action.