You need to read the second-generation ID card to cancel your mobile phone. There is no such thing as "degaussing" an ID card. As long as the chip can't read the information, it needs to apply for an ID card again to cancel the mobile phone number in the business hall.

People's Republic of China (PRC) Identity Card Law

Article 11 If the State decides to issue a new generation of resident identity cards, the validity period of the resident identity cards expires, the names of citizens change or the documents are seriously damaged and unrecognizable, citizens shall apply for new cards; If there are errors in the registration of resident identity cards, the public security organ shall promptly correct them and issue a new card; When you get a new card, you must return the original card. If a resident identity card is lost, it shall apply for a replacement.

Article 10 To apply for a resident identity card, a registration form for applying for a resident identity card shall be filled in and a residence booklet submitted for examination.