Originally Posted by JSanders
Is your old device "off" the network, no SIM and not communicating with the carrier? Yes, you can delete those contacts now, or even wipe the device.
Old device is currently off the network, I will wipe the device, but I would like to put a different SIM in it as a "backup" phone. Will the PIN reappearing on the network (but under a different phone number/SIM) cause any troubles?