How can I cancel my contract with Karl?

You can cancel your contract at any time directly in your account here. Select the relevant policy and tap "Cancel insurance policy". Cancellation takes effect at the end of the current insurance period, and you stay covered until then; there is no refund for the current period. Within the first 14 days after signing, you can instead withdraw, as long as you haven't reported a claim by then, and get a full refund of your premium.