You want to avoid abrupt change in thickness in your composite layup; this will lead to stress risers which are not good for fatigue life. Make sure you have surfaces in your finished model as is the case in the real wind turbine blade. Your model should be like the real turbine blade. If you do the layup properly, you should end up with a linearly varying thicknesses due to ply drop-offs; you should not have abrupt changes in thickness. If the linearly varying thickness is not good enough for you, you can achieve a smoother thickness change by using a CAD surface to extrude the composite layup into a solid model (I assume you want to create the solid model):
You will find more information in the ACP help:
Let me know how it goes.