Head to the BotSpace Dashboard, Once you have a created a template (Ex. unsubscribe_test) with the CTA button option as Unsubscribe, and got it approved.
Head to Automation in the BotSpace Dashboard and click on Create Workflow. Enter the Workflow name you would like to use (Ex. unsubscribe_test).
Click on Set up triggers and the click on Contact replies to a template message and select the template you would want to use (Ex. unsubscribe_test) and then click on Save.
Under the Unsubscribe button click on the + and from the right side menu under Contact, select Unsubscribe. Make sure to turn on the Toggle in the top right corner of your screen to activate the flow.
This will also make sure that the clients who select unsubscribe will not receive broadcast messages going forward.