The CV or Constant Velocity joint allows you to turn the wheel and provides power to the wheel in the same force as if the wheel were straight.
If the car is pulling to one side, then the problem CV joint is on the same side causing the drag.
Even if the CV joint were disconeccted and perfect, it would still drag on the side with the problem.
Most will recommend you change both sides at the same time, but economics don't always permit that.
After the replacement, you should consider an alignment