My daughter also has that "我地要返, 佢不肯發脾氣" when she was 8 months old. You can try to find something else to TRADE with him. You cannot just take away from him, actually this is a good sign that your son is growing. Young child is very easy to distract, simply find something to show him, i am sure he will let go the things that you want to get back. ok?