How To Reset Panasonic Sa-ht740 I Have A Panasonic Phone System At My Business I Just Purchased. Former Owner Lost Password How Do I Reset?

I have a panasonic phone system at my business I just purchased. Former owner lost password how do I reset? - how to reset panasonic sa-ht740

Voice mail is attached to a module for Panasonic, not the reset button on the phone system will reset the voice mail. I would welcome the change, but I am determined!