How do I get the password for a user on my refurbished macbook or delete this usernamed test?

Good day to you Rattletrap67, 

On your Mac, removing a user isn’t difficult and we'll show you how. You will need to have an administrator user set up. That will allow you to manage other users.

The following article goes over how to delete a user and what options you have with that user’s Home folder in the process. 

Delete a user or group on Mac

Let us know if you have any questions.