Given a binary tree, delete a node from it by making sure that tree shrinks from the bottom.

bdelete.js

const rightMost = tree => {
  if(!tree.right){
    return tree;
  }
  return rightMost(tree.right);
}

const deleteRmt = tree => {
  if(!tree){
    return;
  }

  if(tree.right.data === undefined){
    delete tree.right;
    return;
  }
  return deleteRmt(tree.right);
}

const deleteNode = (tree, key) => {
  const rmt = rightMost(tree);
  const axe = [tree];

  while(axe.length){
    const chosen = axe.shift();

    if(chosen.data == key){
      chosen.data = rmt.data;
      rmt.data = undefined;
      deleteRmt(tree);
      break;
    }else{
      chosen.left && axe.push(chosen.left);
      chosen.right && axe.push(chosen.right)
    }
  }
}