In the watch management portal, you can activate the setting "beep before alert", which allows the wearer to cancel the emergency call within 10 seconds before the alert is effectively triggered.

The wearer also has the option to end the alert on the watch. In this case, with the subscription FRIENDS & FAMILY, all helpers will receive an "All fine!" notification. 

The emergency call center will not notify the stored contacts in case of false alerts. 

See also: How can I end a call on the watch?