[SalesForce] Count of DataExtension Rows from API

The following solution seems to be working for me.

    <soap:Body>
    <RetrieveRequestMsg xmlns="http://exacttarget.com/wsdl/partnerAPI"
        xmlns:ns2="urn:fault.partner.exacttarget.com">
        <RetrieveRequest>
          <ObjectType>DataExtensionField</ObjectType>
          <Properties>Name</Properties>
          <Filter xsi:type="SimpleFilterPart" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
            <Property>DataExtension.CustomerKey</Property>
            <SimpleOperator>equals</SimpleOperator>
            <Value>DE_Appointment_Reminder_H2882</Value>
          </Filter>
        </RetrieveRequest>
    </RetrieveRequestMsg>
</soap:Body>

Thanks Kelly and Brodrick from ET for help.

There is an own functionality for this. Import all those records (subscriber-keys) to a particular dataextension. Let Salesforce support enable Contact Delete process for you (no costs).

When it is enable click inside the contact builder and you will find a contact delete button on the top right, where you can select a data extension for all records you want to delete.

Be aware that you have to set the contact delete configuration (how many days they will be kept under suppress status inside contact configuration).

When you delete the contact you will delete the contacts on every dataextension and in dataviews.