We didn’t find deletion information, unfortunately. Generally it seems Conrad takes privacy very seriously. Our advice is to send them an email requesting deletion. Obviously, you should do this from the mail address known at Conrad (linked to your account).
If you’re in Germany, you could use this form: https://www.conrad.de/ce/de/ContactSend.html
In The Netherlands, you could use this form: https://www.conrad-electronic.nl/infocenter/contact.php
Otherwise, search on your local Conrad site for contact information, or try email@example.com.