How to cancel my premium subscription?

https://support.chess.com/article/585-how-does-membership-renewal-work
go to membership and go to manage membership, and click on cancel premium membership, and you're all done

Please cancel my gold membership
Sorry. It doesn't work that way.
Your first mistake was to add a post in a 3 year old thread. Things have changed. You can't send an email to support any more.
https://support.chess.com/en/articles/9831222-how-can-i-cancel-my-membership