Summary
Because Braintree doesn't offer a good way to allow subscribers remove payment methods, we should at least provide messaging to contact us with the last 4 digits of the card they want to remove. Below is from Braintree in the link.
IMPORTANT We do not recommend enabling Vault Manager if you are using Braintree's recurring billing; doing so would give your customers the ability to delete payment methods associated with subscriptions.
Summary
Because Braintree doesn't offer a good way to allow subscribers remove payment methods, we should at least provide messaging to contact us with the last 4 digits of the card they want to remove. Below is from Braintree in the link.