You are free to cancel your membership anytime, there is no tie in or minimum term.
If you joined via the website you can cancel directly with your payment provider
Cancel Credit/Debit Card (if you paid by card it will display below or it will just show "not a subscriber" meaning you paid with PayPal or in app..
..alternatively if you joined via the app you can cancel directly in your iTunes account.
How do I cancel iTunes subscription
And for Google Play
How I do cancel Google Pay subscription