Hi anyone knows if there is any trick to remove the screw plug on the switch's faceplate?

No tricks.

Just use a small flat head screw driver, push it from the edge and pry it off. You might need to do it again at the opposite side (180 degree) from the first point.

I recommend you use the fine tip screw drivers for spectacle/glasses, they are finer and leave a slight mark; barely noticable. If careful enough, leave no mark.

If re-using the screw plug, don't push it in too deep so easier to remove next time.