I want to terminate process if user navigate away from sail form....

You can add a timer based exception to the task and connect the exception flow to a terminate node. Once the configured timer value is reached, the task will get auto submitted and in turn the process will get terminated.

If it's the first form, use the Start-Form.

I want to terminate process if form is left without any activity on it for 2 min. If i configure 1 min exception it will terminate process even if user is working on it..

Try escalating the task to any administrator and then from there the admin can terminate the process after certain amount of time

I vote for the solution proposed by malathik.