Given a nested html lists return the top level.

aTopLevelList.js

// used to simplify: http://www.databaseanswers.org/data_models/index.htm
// and http://www.databaseanswers.org/data_models/index_all_models.htm

var parentList = document.getElementsByTagName('li');
for(var x = 0; x < parentList.length; x++) {
  var childList = parentList[x].getElementsByTagName('ol')
  for(var y = 0; y < childList.length; y++) {
    childList[y].remove()
  }
}

draft_1_SecondLevelList.js

// used to simplify: http://www.databaseanswers.org/data_models/index.htm
// and http://www.databaseanswers.org/data_models/index_all_models.htm

var parentList = document.getElementsByTagName('li');
for(var x = 0; x < parentList.length; x++) {
  var childList = parentList[x].getElementsByTagName('ol')
  for(var y = 0; y < childList.length; y++) {
 
    var parentList2 = childList[y].getElementsByTagName('li');
    for(var a = 0; a < parentList2.length; a++) {
      var childList2 = parentList2[a].getElementsByTagName('ol')
      for(var b = 0; b < childList2.length; b++) {
        childList2[b].remove()
      }
    }
  }
}

draft_2_Not_Working_NeedsHTMLCollectionConversion.js

// used to simplify: http://www.databaseanswers.org/data_models/index.htm
// and http://www.databaseanswers.org/data_models/index_all_models.htm

const findChildItems = (domValues) => {
  var parentList = domValues.getElementsByTagName('li');
  
  var childList = document.createDocumentFragment().children
  if(parentList){
    for(var x = 0; x < parentList.length; x++) {
      childList = [...childList, ...parentList[x].getElementsByTagName('ol')]
      console.log(childList)
    }
  }
  return childList
}
const removeItems = (list) => {
  for(var x = 0; x < list.length; x++) {
    list[x].remove()
  }
}

removeItems(
  findChildItems(
    document
  )
)

// removeItems(
//   findChildItems(
//     findChildItems(
//       document
//     )
//   )
// )