code: public void removeMin() {
      	if (root == null) return;
  
          // if both children of root are black, set root to red
          if ((root.left == null || !root.left.red) && (root.right == null || !root.right.red))
              root.red = true;
  
          root = removeMin(root, true);
          if (root != null) root.red = false;
          else first = last = null;
      }
docs: Remove the first element.