To my knowledge, there is no way to expose/extract the Spotify, or any other non-Sonos password from the Sonos controller. Your best bet would be to go to Spotify, change your password there, then enter it into both your Sonos setups.
If using iOS, go to Settings > Passwords and retrieve your stored Spotify password that way.
Around 7 years ago it was possible to extract every username and password for all Sonos-connected music services from the system.
However Sonos locked it all down, and now the system only stores Oauth tokens, not usernames/passwords.
However you could still clone your home system to the office, crudely, by taking a speaker from home to the office and adding new devices to it there, as a kind of divorced-system. No way to keep them in sync once you take this step, and will get really messy for voice integration, but if you are desperate it will work.