If a guest requests that you do not record the conversation, you are able to do so using the Web Conference. Just click the Stop Record button on the left-hand nav:
If you choose to disable the recording, a visual announcement is made to all guests. When you end the meeting, you can still summarize and log the activity as normal but it will not be possible to coach your activity or playback the recording in Jiminny.
Note: at present, once you have disabled the recording you cannot later re-enable it.