How to change the name after immigration? Can I stop using hanyu pinyin after the change?

Actually, legally speaking, your China nationality, passport, ID card, household registration book, etc. All of them are invalid after you enter other nationalities.

But if you don't cancel, people will still know.

If it doesn't work, use the name on the changed passport.

But it is suggested to use China's name as the middle name. If you don't like it, omit it and write an initial name. When you really need your full name, it's actually good to avoid repeating it to others. China's name is popular in the west now.