That would be a widget, which you can administer from the widgets section in the dashboard (Appearance > Widgets) or the Widgets panels in the customize screen.
Thank you for that. I saw no option to not have something in the right sidebar and have changed it to an image option now so that nothing is displayed, which for me is more preferable than the posts. Is there any way to remove the concept of the right sidebar and have the posts displayed on the page more centrally?