Ease of changing configurations of PVC is one of the big advantages of using it. You can not take joints apart, the pipe must be cut and appropriate fittings and pipes solvent glued where you want them. There are a couple of things about what you have that raise a couple of questions. The small size of the photos make it difficult to tell what size the pipe is. Typically tubs have only an 1-1/2" drain which is adaquate for a tub, but washers need a 2" drain due the the high volume of water discharged very quickly. In addition, I see no trap or vent, both of which are needed for the drain. By the way, you can't decrease the size of a drain as you head downstream.