Vuvie membership is billed through the app store where you subscribed, so cancellation happens there.

iPhone or iPad: Open Settings → your name → Subscriptions → Vuvie, then choose Cancel Subscription.

Android: Open Google Play → profile picture → Payments & subscriptions → Subscriptions → Vuvie, then choose Cancel subscription.

Cancelling stops the next renewal. Your membership stays active until the end of the period you already paid for.