Currently, it is not possible to remove the default value set for a dropdown, radio button form field from the user interface. This can be done in the form XML using the steps mentioned below
Below is an example to remove the default value 'Not specified' from the drop-down field 'Suffering from other cancer?' of the form 'Cancer Details'
- Go to edit page of the form 'Cancer Details'
- Click on 'Export' button to export the form XML file
- Open the downloaded form XML file in a text editor (If the zip file is downloaded, unzip the file and open the form XML file in a text editor)
- Remove the value 'Not Specified' from the tag '<defaultValue><![CDATA[Not specified]]></defaultValue>'
- Save the form XML and import back. (If the downloaded file has the permissible values folder, then zip updated form XML file along with the PVs folder and import back)
- Refresh the browser, the 'Not specified' value will not be the default value for further data entry
Refer wiki page for more details on export/import of a form
Reimporting the form will not affect the existing data.