Car alarm keeps going off

Hey, I keep having trouble with my car alarm going off in my 2006 Prius. It seems to especially go off at night for some reason but I keep feeling the need to disconnect the negative terminal to let my neighbors keep their sanity. The alarm keeps going off even if my keys are not in my pocket. I thought it could be overgrown bushes that were too close to my car so I trimmed them back. I took the sun glasses out of the compartment because someone said that even that could cause the alarm to go off. I even replaced the door sensor in the driver's door. As far as the door sensor goes I rarely open the other doors so I figured the driver's door was the most likely to be the problem but it probably could be another door since I did not replace all of the door sensors in an effort to save funds. What else could be causing the alarm to go off? Also is there a way to deactivate the alarm?

 

Is there a way to access techstream without paying a ton of money for a diagnostic system?