See: *https://support.mozilla.org/en-US/kb/customize-items-on-firefox-new-tab-page *https://support.mozilla.org/en-US/kb/customize-your-new-tab-page You can use "Delete from History" in the three-dot menu of a tile to remove a specific tile. Best is not to use "Dismiss" in the three-dot menu of a tile as this adds the hashed domain to browser.newtabpage.blocked in <b>about:config</b> and this pref can become quite large. *https://support.mozilla.org/en-US/kb/about-config-editor-firefox