to take the plug of a piece of electrical equipment out of the place where it is connected to the electricity supply

Did you unplug the iron? 你拔下熨斗的插头了吗？

to remove what is blocking something

The video shows you how to unplug a bath drain full of hair. 这段视频向你展示如何疏通一个完全被头发堵塞的浴缸下水道。