Those kinds of worksflows are defined through special metadate in the PDF, so you would not find anything about this, when looking into the form in Designer.
Open the form in Acrobat and look into the metadata under the file properties or by typing this.metadata; into the JavaScript console.
You'll propably find entries under the namespace adhocwf. If you want get rid of it you need to delete the corresponding metadata entries. This can be done with an bit JavaScript in Acrobats action wizards.
var oDoc = this,
oXML = new XML(oDoc.metadata), //Load current metadata into XML object
//Declare namespaces used in metadata
nsRdf = new Namespace("http://www.w3.org/1999/02/22-rdf-syntax-ns#"),
nsAdhocwf = new Namespace("http://ns.adobe.com/AcrobatAdhocWorkflow/1.0/");
//Delete unwanted metadata nodes from XML object
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::version;
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::allowAnonymous;
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::dataSetLocId;
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::dataSetName;
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::destUrl;
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::distributionMethod;
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::initiator;
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::state;
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::submitButtonInfo;
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::workflowId;
delete oXML.nsRdf::RDF.nsRdf::Description.nsAdhocwf::workflowType;
//Overwrite PDFs metadata with XML object (works only from batch, not console!!!)
oDoc.metadata = oXML.toXMLString();