You can request the deletion of your customer account in your customer account under "Profile". 

Before contacting us to delete or deactivate your customer account, please ensure that all contracts have been terminated and that there are no outstanding invoices. Devices that are still listed in your customer account under "Toll Box Management" must be returned to us or, if lost, blocked for a fee.

Of course, we comply with the GDPR when it comes to deleting and storing personal data.