I haven't applied for yearly subscription. I have been using free membership trail for the past one month. But suddenly on 22/05/2020 my free membership subscription got renewed and charged me 100$ without my knowledge. I want to cancel my subscription and I need those money back. It just happened without my knowledge. I kindly request you to help me overcome this and get my money back as i have to pay school for my son. Thank you.
You need to open a ticket with support.
https://support.chess.com/article/346-contact-us
Almost all trials of services work the same way. You get the trial, provide payment details, and if you don't cancel before the trial is up, you pay the subscription cost.
It isn't unique to the site and the process is clear. The site does offer a 39-day money back guarantee as well, for first time purchases, and often renewal, so there is minimal risk for most people.