When I go by a text editor into the workspace.xml file and edit the description of the appropriate RunManager:
<component name="RunManager" selected="TestNG.C:/Users/pgangnus/IdeaProjects/idm-apitesting/src/test/testng.xml">
in the line:
<option name="USE_DEFAULT_REPORTERS" value="false" />
But still I do not see how to set it from the IntelliJ IDE.