twitter.com.js

if (!window.location.pathname.startsWith('/settings')) {
  var garbage = Array.prototype.slice.call(
    document.getElementsByClassName('dashboard')
  );

  garbage.push(
    document.getElementsByClassName('trends-inner')[0],
    document.getElementsByClassName('wtf-module')[0]
  );


  for (var i = 0; i < garbage.length; i++) {
    garbage[i].remove();
  }

  document.getElementById('timeline').style.float = "none";
}

updated to ignore settings pages where you need those extra boxes