I created a firefox add-on with the following lib/main.js:
const {Cc,Ci} = require(\"chrome\");
var pref = Cc[\"@mozilla.org/preferences-service;1\"].getServ
Here's how I did it just now:
function clearPrefBranch(aPrefBranchName) {
var defaultBranch = Services.prefs.getDefaultBranch(null);
defaultBranch.deleteBranch(aPrefBranchName);
}
Then, just call clearPrefBranch with an argument of extensions.mypluginname (assuming you used the naming convention, and you should be able to delete all of your extension's installed preferences.
EDIT:
The code I used inside of my main.js file:
const {Cc,Ci,Cm,Cr,Cu} = require("chrome");
Cu.import("resource://gre/modules/Services.jsm");
exports.onUnload = function(aOptions, aCallbacks) {
MyPlugin.shutdown();
};
function clearPrefBranch(aPrefBranchName) {
var defaultBranch = Services.prefs.getDefaultBranch(null);
defaultBranch.deleteBranch(aPrefBranchName);
}
var MyPlugin = {
shutdown: function() {
prefLoader.clearPrefBranch('extensions.oopstab');
}
};