It’s pretty easy to cancel your Shudder subscription. If you subscribed through Shudder, click on My Account while signed into the Shudder app. Then, under Membership Settings, click Cancel Membership.
If you subscribe to Shudder through a third party (Amazon, the Apple Store, Google Play, iTunes, Roku, or YouTube TV), you’ll have to have to go through them instead of Shudder. But the steps are similar.