A knowledge base article about My phone was lost or stolen. How do I do the 2-Step? provided by the UC Berkeley IT Service Hub - Knowledge Portal
Did you set up a second device or print out backup passcodes? If so, use that second device or a passcode to complete the 2-Step process and delete the lost device using the following steps:
If you don’t have a second device or backup passcodes, email calnet2-stephelp@berkeley.edu or Submit a ticket for help.