To clear the alarm history on the Simon XTi, please see the following steps.
1- Press the settings button (the gear icon) in the bottom right hand corner of the screen.
2- Now you will see Panel Status as the third option on the screen. To the right of this you will see Listen and Clear. Press Listen and then Clear and Listen again.
3- You may have to repeat step 2 more than once. If the panel says System OK when you press Listen, then the alarm history has cleared. Now press the close button in the top right hand corner of the screen.