Use your smartphone (or Amazon Alexa) to stop the currently running zone or put the rachio in standby mode. You can start a schedule again or restart all schedules from you smartphone.
rachio is designed to be controlled using a smartphone/tablet or a web browser. It is not designed to be controlled from the rachio unit. To me that was the one of the main features of the rachio. I no longer have to go to my garage to start or stop a zone. Fixing, adjusting and testing sprinklers is so much easier and convenient using my smartphone.
My old rain bird controller had a switch to cancel watering but did not pause watering. But I agree a pause/resume function would be nice.