Many groups set up text message threads, and have a need at times to remove certain users from the message string. I realize you can create a new text message, but the point is, they'd like to retain the message history. A similar way to think of this is like email where you start a email string, reply to all, but need to drop certain people off the conversation as it's not relevant anymore.

Example:
Admitting Representative A messages the group "Admitting". This, in turn, messages all the Admitting staff when Admitting Representative A only meant for the message to go to Admitting Representative B. If there was an ability in Vocera to remove participants from a text message conversation after created, Admitting Representative A wouldn't have to take the extra work to create a new text message and then send it to the correct person, rather, they would be able to remove all participants as needed.