A renewal charge after you believe you've cancelled usually comes down to one of three things.
Deleting the app does not cancel your subscription: your subscription is tied to your account, not the app itself, so removing the app from your phone will not stop the next renewal charge.
It's also possible you have more than one active subscription. If you've subscribed more than once, for example through the website and again through the App Store or Google Play, cancelling one does not cancel the other.
If you cancelled through the website but a charge still went through, this can happen when the cancellation is submitted after that billing cycle's renewal has already started processing.
Contact support and we will check every subscription linked to your account and confirm exactly what's active, and ensure that you are not charged again.