How to cancel the calling card of China Unicom if it is no longer used?

If the mobile phone card doesn't have any account cancellation restrictions and contracts, you can bring the owner's valid certificate to the local business hall to cancel the account. Otherwise, the mobile phone number will be automatically cancelled if it is in arrears for 90 days, but there will still be a late fee of three thousandths of the arrears every day. The owner's ID card will be blacklisted by Unicom, and the owner's ID card can no longer handle any business in Unicom. When the arrears reach a certain amount, the relevant departments of China Unicom will inform users to pay the arrears, and if they don't pay them, they will sue the owner.