What you are asking is very complicated. Looks easy enough until you realise that you are connecting a 0Ω resistor across a voltage source. The current you would get if that 0Ω was ideal, and the capacitor is ideal:
$$ I = \frac{V}{R} = \frac{V}{0\Omega} = \infty A $$
The time it would take to discharge the capacitor is zero seconds., since the time constant is also zero:
$$ \tau = R \times C = 0\Omega \times C = 0 $$
So you have inifinite current passing for no time, which doesn't make sense at all.
In reality the capacitor is not ideal, and the wire you use to short circuit the capacitor is not 0Ω. So the first thing you need to find out is what is the actual resistance between the capacitor's terminals when you "short circuit" it.
The other thing you need to know is the equivalent series resistance (ESR) of the capacitor, and that will not be trivial. It is highly dependent on rate of discharge, temperature, and other factors.
Lastly, the physical loop you form (around which current will flow) has inductance, which will depend on loop area, and whatever else is present inside the loop. Inductance will have the effect of preventing current from rising instantly, further complicating your calculations.
In short (pun intended) you are asking for something way beyond a simple formula, and you can easily damage the capacitor by discharging it in this way.