I could be wrong but I think you do it just like you would if you were canceling a normal premium membership: https://support.chess.com/customer/en/portal/articles/1444834-how-can-i-end-my-premium-membership-subscription-
Canceling free trial
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I got 9 days left on trial, just wanna be sure how to cancel trial when I need to. Anynone knows how to cancel it ? Step by step if possible.