We always advise offering an opt-out in your message as it ensures that you do not contact anyone that doesn’t want to be contacted again.
Here you have 2 options:
If you already have a reply number, you can simply ask them to reply STOP to your number. For example, ‘Reply STOP to unsubscribe’
If you don’t have a number, we can offer a personalised STOP keyword on our shared short-code; 82228.
Here you can keep it short and sweet if you don’t want to use up too many characters. For example, ‘Opt-out? Text SBSTOP to 82228’
You will need to put this caption in the body of your message somewhere.