Disable or enable MonsterInsights (GA) tracking and force delete of _ga and _gid cookies if Cookie Notice consent is rejected.

mi-cookie-notice-with-ga-cookie-removal.js

function clearCookie1112686(name, domain, path) {
  try {
    function Get_Cookie(check_name) {
      // first we'll split this cookie up into name/value pairs
      // note: document.cookie only returns name=value, not the other components
      var a_all_cookies = document.cookie.split(";"),
        a_temp_cookie = "",
        cookie_name = "",
        cookie_value = "",
        b_cookie_found = false;

      for (i = 0; i < a_all_cookies.length; i++) {
        // now we'll split apart each name=value pair
        a_temp_cookie = a_all_cookies[i].split("=");

        // and trim left/right whitespace while we're at it
        cookie_name = a_temp_cookie[0].replace(/^\s+|\s+$/g, "");

        // if the extracted name matches passed check_name
        if (cookie_name == check_name) {
          b_cookie_found = true;
          // we need to handle case where cookie has no value but exists (no = sign, that is):
          if (a_temp_cookie.length > 1) {
            cookie_value = unescape(a_temp_cookie[1].replace(/^\s+|\s+$/g, ""));
          }
          // note that in cases where cookie is initialized but no value, null is returned
          return cookie_value;
          break;
        }
        a_temp_cookie = null;
        cookie_name = "";
      }
      if (!b_cookie_found) {
        return null;
      }
    }
    if (Get_Cookie(name)) {
      var domain = domain || document.domain;
      var path = path || "/";
      document.cookie =
        name +
        "=; expires=" +
        new Date() + // If Date() doesn't work hardcode this "Thu, 01 Jan 1970 00:00:00 UTC"
        "; domain=" +
        domain +
        "; path=" +
        path;
    }
  } catch (err) {}
}
(function () {
  function cleanGaCookies() {
    clearCookie1112686("_ga", ".YOURDOMAIN.com", "/"); // Change to your domain.
    clearCookie1112686("_gid", ".YOURDOMAIN.com", "/"); // Change to your domain.
    console.log(`Cleared GA cookies. document.cookie = ${document.cookie}`);
  }

  /* Check for Cookie Notice plugin opt-out. */
  const cookieNotice = document.cookie
    .split("; ")
    .find((row) => row.startsWith("cookie_notice_accepted="));
	
  if (!cookieNotice) {
    /* If no consent cookie, tell MI not to track. */
    __gtagTrackerOptout();
    cleanGaCookies();
    console.log("MonsterInsights opt-out: no cookie");
    return;
  }
  const consent = cookieNotice.split("=")[1];

  console.log(`\nCookie Notice consent: ${consent}\n\n`);

  // MI doesn't have a way to opt back in (revoke).
  // So, we'll manually say it's cool to track again.
  if (consent === "true") {
	  const disableStr = 'ga-disable-UA-1234567-1'; // Change to your tracking ID.
	  document.cookie = disableStr + '=false; expires=Thu, 31 Dec 2099 23:59:59 UTC; path=/';
	  return;
  }

  /* If consent not given, tell MI not to track. */
  __gtagTrackerOptout();
  cleanGaCookies();
  console.log("MonsterInsights opt-out: consent rejected");
})();