Cancel a registered alarm.
http://api.onebusaway.org/api/where/cancel_alarm/1_00859082-9b9d-4f72-a89f-c4be0e2cf01a.xml
<response>
<version>2</version>
<code>200</code>
<text>OK</text>
<currentTime>1270614730908</currentTime>
<data>
<references/>
</data>
</response>
The alarm id is returned in the call to register-alarm-for-arrival-and-departure-at-stop api method.