HI Mister-X, when you check/uncheck a one-click search engine on the Options page, or use the Remove button below the list, your choices are stored in a separate file called search.json.mozlz4 instead of prefs.js. The about:config page doesn't show settings from or allow changing settings in search.json.mozlz4.

Is there a problem with making the changes through the Options page?

Or did you want a Policy approach to removing search engines? Since the built-in search engine plugins are implemented as extensions, you can "uninstall" them to deactivate them.

This article describes how you create a Policy file: Customizing Firefox Using policies.json.

The contents of the policies.json file would be along the following lines:

{
  "policies": {
    "Extensions": {
      "Uninstall": [
        "amazondotcom@search.mozilla.org",
        "bing@search.mozilla.org",
        "ebay@search.mozilla.org",
        "twitter@search.mozilla.org",
        "wikipedia@search.mozilla.org"
      ]
    }
  }
}

As you can see, the list contains the search extension IDs you want to remove, separated by commas. (Writing them on separate lines is merely cosmetic.)

Hi jscher2000

thanks for your reply, I already have an entry in policies.json, how can I add a second one ?

{

 "policies": {
   "Bookmarks": [
     {

"Favicon": "test",

       "Placement": "toolbar",
       "Title": "text",
       "URL": "https://google.com"
     }
   ],
   "DisplayBookmarksToolbar": true
 }

}

   "Extensions": {
     "Uninstall": [
       "amazondotcom@search.mozilla.org",
       "bing@search.mozilla.org",
       "ebay@search.mozilla.org",
       "twitter@search.mozilla.org",
       "wikipedia@search.mozilla.org"
     ]
   }
 }

}

Does this work? Yours had some extra } characters:

{
  "policies": {
    "Bookmarks": [{
      "Favicon": "test",
      "Placement": "toolbar",
      "Title": "text",
      "URL": "https://google.com"
    }],
    "DisplayBookmarksToolbar": true,
    "Extensions": {
      "Uninstall": [
        "amazondotcom@search.mozilla.org",
        "bing@search.mozilla.org",
        "ebay@search.mozilla.org",
        "twitter@search.mozilla.org",
        "wikipedia@search.mozilla.org"
      ]
    }
  }
}

no, One-Click is still there

jscher2000's solution is working great for me.

Are there any errors in about:policies?

please check the attachments

What version of Firefox are you using? Are you using the ESR?

I have 76.0.1 x64

I'm at a loss. That exact same JSON is working for me.

Are there any errors on the JS console (Ctrl+Shift+J)

Try to delete search.json.mozlz4 in the profile folder to see if that has effect.

still the same problem

I'm at a loss. This is working for me locally.

Note we do provide an official policy for this but it is ESR only.