Unfollow all pages i've liked on facebook - Go to https://www.facebook.com/[YOURUSERNAME]/likes & Scroll down to show all pages & execute this script in the console

unfollow.js

counter=0; var ids = [];
for(var i=0; i < document.getElementsByClassName('_42ft _4jy0 _5lzj _3spg _4jy3 _517h _51sy').length; i++){ 
var  d = document.getElementsByClassName('_42ft _4jy0 _5lzj _3spg _4jy3 _517h _51sy')[i];
  if(!/hidden_elem/g.test(d.className)){
    counter++;
    ids.push(i);
  }
} 
console.log(counter);

var t = setInterval( function() {
  if(ids.length==0)
    clearInterval(t);
var s = ids.pop();
document.getElementsByClassName('_42ft _4jy0 _5lzj _3spg _4jy3 _517h _51sy')[s].click();
}, 100);