To remove properties that are part of the data source definition, set the values of those properties to null (Nothing in Visual Basic).
If you set the CredentialRetrieval property of the data source definition to Integrated or Prompt, do not supply values for UserName or Password. Doing so results in a SOAP exception with the error code rsInvalidElementCombination.
If you set the CredentialRetrieval property of the data source definition to Integrated or Store, any value you supply for the Prompt property is not saved.
With subscriptions, it may be necessary to store credentials in the report server database so that the subscriptions can run unattended.
Setting the ConnectionString property of the data source definition to null (Nothing in Visual Basic) results in a SOAP exception with the error code rsInvalidXML. If you do not want to supply a value for ConnectionString, set its value to an empty string ("").