What is the effect of removing some so3 from a system initially at equilibrium?

The reaction is as follow,

                             2 SO₂(g) + O₂ (g)     ⇄     2 SO₃ (g)

According to Le Chatelier's Principle," when a system at equilibrium is subjected to any external stress (like changing temperature, pressure or concentration) the system will tend to adjust itself in such a way to minimize the effect of that stress.

In given reaction, when the equilibrium is disturbed by removing SO₃ from the system then the equilibrium will shift in the forward direction resulting in consumption of more reactants. Or if the Oxygen gas is in excess then the concentration of SO₂ will decrease more.

Only one reactant yields 2 or more products. meaning you will only have 1 product and it will break down into 2 or more products. eg. h2o -> h2 + o2