clearPref("app.update.lastUpdateTime.search-engine-update-timer");
defaultPref("browser.search.geoSpecificDefaults", true);
defaultPref("browser.search.geoip.url", 'data:application/json,{"country_code": "US"}');
defaultPref("browser.search.geoSpecificDefaults.url", 'data:application/json,{"interval": 315360000, "settings": {"searchDefault": "Wikipedia (en)", "visibleDefaultEngines":["wikipedia"]}}');

----

Is this really about Firefox 45esr? You can't delete builtin search engines as those are stored in one of the omni.ja archives. *[67 and older]: resource://search-plugins/ *[68 and newer]: resource://search-extensions/ The list.json file specifies what search engine are enabled for a specific region. *resource://search-plugins/list.json *https://searchfox.org/mozilla-esr45/source/browser/locales/en-US/searchplugins/list.txt *https://searchfox.org/mozilla-release/source/browser/components/search/extensions/list.json You can try this code in autoconfig.cfg for Firefox 45esr <pre><nowiki> clearPref("app.update.lastUpdateTime.search-engine-update-timer"); defaultPref("browser.search.geoSpecificDefaults", true); defaultPref("browser.search.geoip.url", 'data:application/json,{"country_code": "US"}'); defaultPref("browser.search.geoSpecificDefaults.url", 'data:application/json,{"interval": 315360000, "settings": {"searchDefault": "Wikipedia (en)", "visibleDefaultEngines":["wikipedia"]}}'); </nowiki></pre> ---- You need to delete search.json.mozlz4 in the profile folder to generate a new file with only this search engine. Note that in Firefox 60 ESR and 68 ESR you can do this via policies.json (this is a ESR only policy). *https://github.com/mozilla/policy-templates/blob/master/README.md#searchengines--remove