I want to cancel subscription but does not give that option. Help

Here's how: https://support.apple.com/en-us/HT202039

This link has additional links that are not covered in the link posted by muguy - How to get a refund and how long it takes.

What does the subscription say for its expiry or renewal date?

If it has the word "Expires" or "Expired" and a date, then it's already been cancelled and there's nothing left to do.