How do you get rid of the News Flash or other modules?
From Joomla! Documentation
Any Joomla! Module can be disabled from the Module Manager. To do so,
- Log in to the Joomla! back end and navigate to the Module Manager.
- Locate the desired Module (for example, News Flash).
- Click on the icon next for this module name in the "Enabled" column. This will toggle the Module between "enabled" and "disabled".