In the watch management portal, you can activate the setting "beep before alert", which allows the wearer to cancel the emergency call within 5 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?