How to update the field value to null using customer update API

Customer APIs Issue: How to Null out an Existing Database Value Using an Update API? (Doc ID 287488.1)

How to pass parameters to the URL in the OAF page

WHen you are calling the new custom page from the standard side menu navigation.The parameters can be passed by using the below code in process request of the controller.
  
  DictionaryData dictionarydata = new DictionaryData();
      dictionarydata.put("ImcPartyId", partyId);
      dictionarydata.put("ImcPartyName", partyName);
      pageContext.setFunctionParameterDataObject(dictionarydata);