Windows locked to single user despite wiping SSD?

During the initial setup or Out-of-Box Experience (OOBE) wizard, Windows establishes a connection with Microsoft services to verify if a PC is associated with Azure Active Directory (AAD) or has Windows Autopilot configured, among other possibilities. If any of these conditions are met, Windows will automatically initiate a reconfiguration process. (To identify the PC, a "hardware hash" from your device is utilized, although Microsoft has not officially disclosed the specific details of its composition.)

• The real way to stop this, it must be released by the prior owner (or their company IT management) from their management control. Maybe ask the seller about it, as they (if they have the authorization and access) can do that on their end.
• If you can't get it removed/reach them. Maybe try reinstalling without letting the machine connect to the network as part of the OOBE (Out-of-box experience). It is possible that once fully setup and logged in to Windows (without being connected) it won't then come back and reconfigure from the company provisioning.