How to make an undeletable folder

It probably happened once, that someone deleted a folder ,which is containing a few hundred files and was very important.If you’d like to avoid anything similar happening in future.You can protect your important folders by making them undeletable. Here is simple tip, which can help you. 1)Open cmd ( Type in Run option cmd or navigate to All Programs->Accessories-> Command Prompt) 2)In cmd change to the directory that you want,I change to E.Just type E: and enter.If you don´t know how change directories with Cmd, here is post where I wrote about it.
3)Type md \lpt1\\ and press enter, the folder will now in your E:
4)If you try to delete or rename it, it will appear error message

How to delete undeletable folder?

Just go to cmd Navigate to the directory and type in rd \lpt1\\