Of course, @CrazyCat! I’d be happy to clarify.
There are only certain dispatch instances that can be cancelled. For this specific instance, a fire alarm dispatch is usually unable to be cancelled. A burglary alarm, however, can be cancelled by disarming as soon as possible.
Check out this help center article which breaks down how each Alarm event is handled for dispatch. You’ll see a special note under each description which will indicate if it can be cancelled or not. 