Read:
https://china.usembassy-china.org.cn/visas/immigrant-visas/us-citizenship-immigration-services-uscis/abandonment-status-form-407/
Or Chinese version:
https://china.usembassy-china.org.cn/zh/visas-zh/immigrant-visas-zh/us-citizenship-and-immigration-services-uscis-2/abandonment-of-status-form-i-407/
https://china.usembassy-china.org.cn/visas/immigrant-visas/us-citizenship-immigration-services-uscis/abandonment-status-form-407/
Or Chinese version:
https://china.usembassy-china.org.cn/zh/visas-zh/immigrant-visas-zh/us-citizenship-and-immigration-services-uscis-2/abandonment-of-status-form-i-407/