Unicom customer service SMS on Xiaomi 3 SMS cannot be deleted.

Try it in the following ways. If it can't be deleted, you can restart your phone or go for after-sales maintenance.

1, enter the notification message first, and press and hold the message.

2. An edit bar will appear at the bottom of the screen. There is a pattern of a dustbin. Check all the boxes and delete them all with one click.

3. Then, delete other short messages in the same way.