I tried all the options from the comments above, but none of them worked for me. In the end, I found the unsubscribe button somewhere else:
-Clicked on my name at the bottom left and selected workspace settings.
-On the left side in the new menu, there’s the Billing option.
-Then it shows the active plan, and on the right there’s a Manage Plan button; if you click it, the Cancel Subscription button appears.