Can I return an item to any Costco or do I have to go to the one I purchase item from .

Any Costco will accept your return. Have your receipt & membership card with you.

You got to Any Costco

You can go to any costco

Yes, as Sandra said bring your receipt and membership card. Also, if you receive a gift purchased at Costco you can return many for a Costco gift card. I even purchased in S Carolina and returned here... no problem.