The cancellation period is 4 weeks before your current contract ends. You can easily cancel your contract in the fleet management portal. If you do not cancel your contract within the cancellation period, your contract will extend automatically for 1 more month. There is no fee/penalty for cancelling your contract.
Please note that cancelling your contract outside of the cancellation period is not possible. If you do not cancel your contract within the cancellation period, it will extend automatically.