code: def reset_defaults(self):
          
          self.save_login.setChecked(False)
          self.save_password.setChecked(False)
          self.save_url.setChecked(False)
  
          set_setting(GEONODE_USER, '')
          set_setting(GEONODE_PASSWORD, '')
          set_setting(GEONODE_URL, '')
  
          self.login.setText('')
          self.password.setText('')
          self.url.setText('')
docs: Reset login and password in QgsSettings.