private void removeAVL(TreeNode startingNode, String searchingKey) {
        currentSearchHeight++;
        if (startingNode == null) {
            System.out.println("\nKey " + searchingKey + " not found.");
        } else {
            if (startingNode.value.compareTo(searchingKey) > 0) {
                removeAVL(startingNode.left, searchingKey);
            } else if (startingNode.value.compareTo(searchingKey) < 0) {
                removeAVL(startingNode.right, searchingKey);
            } else if (startingNode.value.equals(searchingKey)) {
                removeFoundNode(startingNode);
                System.out.println("\nValue " + searchingKey + " removed successfully at tree height " + currentSearchHeight + ".");
            }
        }
    }