If the alarm is going off even after uninstalling SHM (assuming you’ve uninstalled SHM and STHM) then it could be another app that’s triggering the alarm when the sensors are set off. Check that you don’t have an alternative security app installed (eg Intruder Alert with actions or a WebCoRE rule or some other automation) which may be triggering the alarm. If you have the Classic app you can check the recently tab of the alarm device page in My Things to see what’s triggering the alarm.