"Facebook Posts Deleter 2018" script is a User Script to automatically delete Facebook posts one by one without any user intervention. Install this script in Firefox-based browsers (Firefox, Seamonkey, IceWeasel) using the Greasemonkey add-on. Then, go to your Facebook "Activity Log". This scripts was tested in Firefox 34. If you use a much diff…

com.vsubhash.js.facebook-posts-deleter

// ==UserScript==
// @name        Facebook Posts Deleter
// @namespace   com.vsubhash.js.facebook-posts-deleter
// @description Deletes all facebook posts, one by one if browser is spoofed as Firefox 34
// @include     https://www.facebook.com/*allactivity
// @exclude     %exclude%
// @version     2018
// @grant       none
// ==/UserScript==
 
 /*
  * "Facebook Posts Deleter 2018" script is a User Script to automatically delete Facebook posts one by one without any user intervention. Install this script in Firefox-based browsers (Firefox, Seamonkey, IceWeasel) using the Greasemonkey add-on. Then, go to your Facebook "Activity Log". This scripts was tested in Firefox 34. If you use a much different browser, it may not work as Facebook serves different web pages (CSS/JS) for different versions of browsers. To fix that, spoof your current browser as Firefox 34. For this, use a browser ID spoofer add-on (such as User Agent Overrider https://addons.mozilla.org/en-US/firefox/addon/user-agent-overrider/) and with the custom agent string "Mozilla/5.0 (X11; rv:34.0) Gecko/20100101 Firefox/34.0". This script was simplified and tested in 2018 and it works fine.
  */
 
 
document.addEventListener("DOMContentLoaded", startItDelayed, false);

function startItDelayed() {
  window.setTimeout(clickTheMenu, 10*1000);
}


function clickTheMenu() {
  console.log("FPD: Finding the menu");
  arAnchors = document.getElementsByTagName("a");
  for (var i = 0; i < arAnchors.length; i++) {
    if (arAnchors[i].id.indexOf("u_jsonp") > -1) {
      console.log("FPD: Found a menu");
      arAnchors[i].click();
      console.log("FPD: Clicked the menu");
      window.setTimeout(clickDeleteOption, 3*1000);
      break;
    }
  }
}

function clickDeleteOption() {
  console.log("FPD: Finding the Delete option");
  arAnchors = document.getElementsByTagName("a");
  for (var i = 0; i < arAnchors.length; i++) {
    if (arAnchors[i].hasAttribute("ajaxify")) {      
      if (arAnchors[i].getAttribute("ajaxify").indexOf("/ajax/timeline/delete/confirm") > -1) {
        console.log("FPD: Found the Delete option");
        arAnchors[i].click();
        console.log("FPD: Clicked the delete option");
        window.setTimeout(clickDeleteConfirmButton, 3*1000);
        break;
      }
    }
  }
}


function clickDeleteConfirmButton() {
  console.log("FPD: Finding the Delete confirmation button");  
  arButtons = document.getElementsByTagName("button");
  for (var i = 0; i < arButtons.length; i++) {
    if ((arButtons[i].className.indexOf("layerConfirm") > -1) &&
        (arButtons[i].textContent.indexOf("Delete") > -1)) {      
      console.log("FPD: Found the Delete confirm button");
      arButtons[i].click();
      console.log("FPD: Clicked the Delete confirm button");
      window.setTimeout(function() { location.reload(true); }, 3*1000);
      break;
    }
  }
}

Looks like half the script is missing?

No "Delete Facebook Posts" that pops on the top-left for me

Got that button using https://www.facebook.com/*allactivity as included pages instead of https://www.facebook.com/*=allactivity, but when I click it the only thing it does is to show a button for the first shown activity that I must click manually for confirming the action.

In short, it does not work.