1. For the seat part, please check the video below.

2. For removing the Strut (part B) from the base, you just need to pull it up. (for some people, it might be difficult to pull it up. In that case, please ask for help from someone around you. Why might it be difficult? - Once you assembled the product and sit on it, the hydraulic cylinder should already strongly stick with the base and the seat part for customer's safety)