This makes not much sense. The sum does not vanish, it is zero. Zero is not vanishing.
The sum of all torques about ANY point is zero in a system in equilibium.
For an object in equilibrium the sum of the torques acting on it vanishes only if each torque is calculated based on your:
2 answers
Now, for the last"is calculated based on your:" I haven't a clue what the question is asking.