This guide explains how to remove a News Flash category from your site by first unpublishing it, then permanently deleting it.
Instructions
Navigate to Modules and, on the Content tab, select News Flash:

Next to the category, select Choose an Action and then Unpublish:

Locate the category in the Unpublished Categories section. Select Choose an Action and then Delete:

Click OK on the pop-up asking, Are you sure you want to delete this category?:
