There are 2 ways to bypass sensors with the hub:
With any sensor in an Open status or in a trouble condition, arm the system using any method (Frontpoint App, Website, Keypad, etc). The sensor will be put into a bypass status. The sensor will automatically be taken out of the bypass status the next time the sensor is closed or the trouble condition is cleared (e.g. If a window is open when the system is armed and then it is closed, it will be armed and if it gets opened again before the system is disarmed it will set off the alarm).
From the home page of the Frontpoint App, tap on the current arming status on the home screen underneath Security System. Check the box labeled Bypass Specific Sensors, then select your desired arming mode. This will then lead to a page with a checklist of your sensors. Check any sensors on the list to bypass and tap on the ARM button at the top right. Your system will then be armed with the selected sensors bypassed. They can be opened or closed any number of times without setting off the alarm. The sensors will automatically be taken off the bypass status the next time the system is Disarmed.