yes,
there is a write up on how to reset the password for an netvanta switch. you have to connect to it locally using a serial port, during the initial boot up sequence press the ESC key to get in to the boot loader and use the option that allows you to boot without passwords. add a new admin password and save the configuration file and reboot. you will have access.
strongly recommend that you backup your 7100 before you go through this sequence. this would be done by using the CLI and copy the adtran configuration file to another name.
hope that his helps.