You may have noticed the opt-out language "Reply STOP to unsubscribe." embedded into your messages when creating your templates.
If you are an Elite user, you can remove opt-out language from your templates by unselecting the Opt-out Text checkbox right below the message field:
NOTE: We do not recommend removing opt-out language from your initial campaign messages, as it may impact your delivery rate. It's best to remove opt-out language only from the follow-up messages (i.e., messages you send in the drip campaign sequence)
*This feature is not available with the Basic, Starter and Pro plans.