I have my recent Can i return/exchange a kid bike for a smaller bike even though its 11:00pm

Depends on the manager. Some stores do returns around the clock.

Customer service closes earlier than that

I think the service desk closes around 09:00 PM but call first

I would call Customer Service at that Walmart and explain the situation to them...if you have a receipt or not and let them advise you on this-possibly say it was a Christmas present or even a birthday surprise they will be the ones that could tell you....if no receipt they may refund you with a Walmart gift card instead of cash if there is no bicycle in the store to exchange with. Make sure you get the C/S name that you spoke with. Good luck!

I believe they usually close the customer returns earlier, I think 10 but maybe earlier. Call the number on the receipt.

You should be able to.