2000 VW Cabrio alarm goes off for no reason

2000 VW cabrio, and the car alarm has been going off and i have no idea why. It has gone off in empty parking lots, and much to my neighbors annoyance, several times in the middle of the night. Other than unplugging the battery when i get home what can i do about my alarm?

I might guess the doors automatically lock when you turn off the car and exit, if you unlock the door with a key after that will the alarm system rearm? As long as you don’t mind leaving it unlocked.

The remote car opener hasn’t been working properly for a few months so I’ve been using the key to manually lock and unlock the car. After a while the doors automatically lock if i leave it unlocked. So sadly that’s not an option for me.
EDIT:
I’m gonna give it a try at work today. Didn’t lock the car after parking it so we’ll see. Fingers crossed.