Default tool permissions in a Discussion allow all workspace members, except those with the Guest role, to edit any topic.
Select the topic you want to modify and press ENTER.
Edit the topic fields as needed.
Note: The Discussion tool is actually a custom SharePoint Workspace Lists tool, with forms designed via Microsoft Office InfoPath 2010. As such, field editing features correspond to those found in any other InfoPath form. For example, if you select a rich-text field, the Ribbon offers the same text formatting features found in InfoPath for rich-text editing.
If you decide to not save your changes, click the Close box, and then click No when prompted to save your changes.