Suppose we have a stock $X$ at which trades at 100 dollars. We suppose the stock follows a geometric brownian motion. We know that the interest rate is zero and annual volatility is 10 percent. How can we hedge the risk?
You sell your stock $S$ against some cash.
You need a risk model to understand the sources of risk for your stock. If the risk factors can be traded then you can use the factor loadings to hedge your risk.
You first need to define "hedge". Or else the question remains undefined, and the minimum risk is achieved not trading at all ;-)