The easiest way is to set a different Homepage.

Or use one of the UserStyles I created to hide those "snippets". https://userstyles.org/styles/104618/about-home-hide-snippets

This one with also hide the "brand logo" section of about:home which is sometimes change with the "snippet" that is below the "search container". https://userstyles.org/styles/104673/about-home-hide-snippets-and-hide-brand-logo

You'll need the Stylish extension to make use of those UserStyles; which is available from each userstyles page.

Mozilla shows rotating snippets on the about:home page to run different campaigns and these changes regularly. You can consider to set another page as the home page for now or you can wait until this campaign ends.

If you prefer not to see snippets on the about:home page or if there are problems with a snippet then you can set this pref to an empty string value on the about:config page by deleting the current value via the right-click context menu (Modify) or a double-click.

• browser.aboutHomeSnippets.updateUrl (delete current value)

Delete the storage\persistent\moz-safe-about+home folder in the Firefox profile folder with Firefox closed ("3-bar" Firefox menu button > Exit/Quit) to remove snippets stored in IndexedDB and make Firefox use a default snippet set.

You can reset the browser.aboutHomeSnippets.updateUrl pref on the about:config page via the right-click context menu to the default value to re-enable the snippets and make Firefox recreate the moz-safe-about+home folder.

Close and restart Firefox after changing the value of the browser.aboutHomeSnippets.updateUrl pref.

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config