Your customer may wish to be removed from marketing messages. They can do this by sending an SMS to you with the message STOP, STOPALL, UNSUBSCRIBE, CANCEL, END, or QUIT.
To comply with industry best-practice, this will also add them to a Jiminny block list and you won't be able to message them. You should also update your marketing preferences in your CRM.
If your customer changes their mind, they must first text START, UNSTOP, or YES to the number to opt in again.