If it is a factory system it sounds like you have a door switch issue. That would explain both the alarm going off at random and the power drain. The switch works sometimes and the alarm arms, then the switch fails and the alarm thinks someone is breaking into the car. The battery drain is for the same reason, you close the doors and the switch fails, that turns on some of the modules and/or interior lights and drains the battery.
As for disconnecting it, not easily possible because it is not one item, it is spread through multiple modules.
A dealer or decent shop should be able to diagnose the issue and repair it.
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Wednesday, August 9th, 2017 AT 4:01 PM