This tutorial applies to the DHL Versenden module up to version 1.3.1 for Magento 1.x
There will be a configuration option in future versions.
To remove the receiver's phone number from the label, a code modification is necessary. This will remove the number permanently for all shipments.
Edit the file app/code/community/Dhl/Versenden/Model/Webservice/Builder/Order.php
Around line 173 you should find:
$versendenReceiver->phone,
Comment the line out, and directly below it add the following:
'0000',
The result should look like this:
Save the file, and flush all Magento caches.
Instead of the receiver phone number, the value 0000 will be transmitted to DHL and be printed on the label.