The sidebars on your website are controlled by elements called “Widgets”. You can add/edit or remove sidebar items in the “Appearance” section of the admin dashboard.
Login to your admin dashboard and navigate to: Appearance -> Widgets -> Primary Sidebar
What is a Widget? WordPress explains widgets as:
“a fancy word for tools or content that you can add, arrange, and remove from the sidebar(s) of your website”
Sidebar widgets are set on any Page were the Sidebar is selected
If you don’t want the sidebar on a page, go to that page and under the “layout Settings” select the image with the full width option.