To take off (clothes, shoes, hats, etc.); to undress. A transitive verb commonly used in everyday speech.
家に入ったらまず靴を脱いでください。
When you enter the house, please take off your shoes first.
暑くて上着を脱いだ。
It was hot, so I took off my jacket.
子どもが泣きながら服を脱いでしまった。
The child ended up taking off their clothes while crying.
プールに入る前に水着に着替えてシャツを脱いだ。
Before entering the pool I changed into a swimsuit and took off my shirt.