You can delete a customer using its ID. When a customer is deleted, all associated payment methods are also deleted, and all associated recurring billing subscriptions are canceled.

Node.js 
gateway.customer.delete("theCustomerId", function (err) {
  err;
  // null
});

If the customer can't be found, it will return a notFoundError.

Arguments
customerId required, String

A string value representing an existing customer in your Vault.