If you do not have your own Sonos system already it’s ‘sometimes’ easier to factory reset your Sonos devices and just set them up as a brand new Sonos system. However, if you do have an existing Sonos System, then you can ‘perhaps’ transfer the ‘other’ system to your existing Sonos setup, or just transfer the current setup to your own Sonos account/credentials .. so you have a choice. The links below show how to factory reset and setup a new system, or transfer the setup to your Sonos Account.
Sonos Device Factory Reset
New Sonos System Setup
Sonos System Transfer