2 years. Babies aren't able to undress themselves until they become toddlers. They gradually start helping get dressed or undressed, such as by moving their arms and legs into or out of sleeves and pant legs. Soon after, they are coordinated enough to take off their clothes. Putting their clothes back on, however, takes a little while longer to learn.
2 years. Most children can remove clothing by 2 years old, but not necessarily when you want them to do so.