how to remove internet service provider from iPad
AT&T account still showing on the cellular data on my iPad. I stopped subscribing from this provider more than 15 years ago.
It is normal for a provider to issue a Carrier Lock on the device when purchased from them. This is to insure the device cannot be used on another provider until all of the obligations have been met when purchased. The provider does not remove the lock automatically and has to be requested by you. You will need to contact the cellular provider and inquire about removing the lock.