Hello, the operation of dropping out of onion mathematics class can be carried out in the setting center. Joining the classroom is to help users determine their own learning progress, and then choose teaching materials to study according to the progress. If you enter an unsuitable class, you can change directly without returning. Onion Mathematics is a convenient and practical mathematics teaching software, which combines videos and exercises to help children master mathematics knowledge. There are many kinds of teaching materials to choose from, which are completely suitable for children and easy to operate. I hope my answer will help you. You can ask other questions.