I don't want to go after I passed the interview on the spot. How can I politely refuse?

You can tell the truth. If you feel inconvenient to say, you can refer to the following reasons.

First of all. With a better choice, that is, a better work unit, the company can accept this reason.

Second. After consideration, it can be said that the distance is too far.

Third. It can be said that there is an emergency at home and I need to go back to my hometown.

But remember, whatever the reason, you should communicate with the human resources of this company as soon as possible, and you won't go to their company. This matter.

Let people also have a psychological preparation. Don't delay people recruiting. Convenient for others and convenient for yourself.