1. Open the top cover of the drainer, and then put in the hexagon nut.
2. After that, knock the hexagon nut several times with a hammer to make most of it enter the drainage pipe.
3. Turn the nut to the position shown in the figure.
4. Then turn the hexagon nut with a wrench.
5. Turn the wrench back and forth.
6. Turn it over several times and take it out of the sewer.
7. In this way, the drain pipe can be removed and replaced.