If you are managing your opt-out process with an automated workflow, it can be beneficial to disable the automatic opt-out message at the end of SMS messages. To achieve this, follow the steps outlined below.
Click Settings on the bottom left hand corner
Click Phone Numbers -> Advanced Settings -> SMS Compliance
Untick the Following 2 check boxes.
Make SMS compliant by adding an opt out message.
Make SMS compliant by adding a sender information
Repeast the following steps for each of the above options.