Alarm.com cancel/verify is just included on accounts, it is part of the base ADC service and cannot be disabled. You can choose to use it or not, but it does not impact the timing of the monitoring process in the event of an alarm. It gives users a quick way of canceling an alarm or confirming dispatch is needed.
The Alarm Response Messenger is an optional service which is offered through our monitoring station. It performs a similar but expanded role as described in the guide below:
Broadly speaking, ARM delays the processing of alarm signals by the monitoring station, allowing your users a little time to access the notifications and confer within the chat tool if necessary if dispatch is needed or if it is a false alarm. It will probably find the best use on systems with many users who might trigger the alarm accidentally. Businesses, families with older children, etc.