en.javascript.info/2-ui/1-document/07-modifying-document/4-clear-elem/solution.md

First, let's see how not to do it:

function clear(elem) {
  for (let i=0; i < elem.childNodes.length; i++) {
      elem.childNodes[i].remove();
  }
}

That won't work, because the call to remove() shifts the collection elem.childNodes, so elements start from the index 0 every time. But i increases, and some elements will be skipped.

The for..of loop also does the same.

The right variant could be:

function clear(elem) {
  while (elem.firstChild) {
    elem.firstChild.remove();
  }
}

And also there's a simpler way to do the same:

function clear(elem) {
  elem.innerHTML = '';
}