All services Retail memberships

Cancel Costco

Costco has no online cancel button. Its own answer gives two routes only: the primary member speaks to staff at any warehouse membership counter and gets an immediate refund, or calls Member Services on 1-800-774-2678. You can separately switch off Auto Renewal online, which stops the next charge.

Costco has no page we can link to. The steps below are from their official help page.

Open Costco’s help page

What to expect

Notice period, visit or fee

Steps

The primary member takes their membership card and photo ID to the membership counter at any Costco warehouse and asks to cancel, refund is immediate
Or call Member Services on 1-800-774-2678 and speak to an agent
To stop the next charge instead of cancelling, sign in at costco.com, open Account, then Renew Membership, and remove the card set for Auto Renew
Remove Auto Renewal at least two business days before the first of your renewal month, or the card is likely charged and refunded afterwards
Keep the confirmation or receipt

Other countries

Costco runs separate sites and membership systems by country. Cancel in the country you joined.