If you want to create a Folder that no one can delete or modify, then you are in the right place. Usually, if you want to create a folder in a windows machine, you can directly right-click on any window and choose New > Folder. Also, you can create a folder using the command prompt also. While creating a Folder you need to enter any name, If you didn’t enter it will create under the default name(New folder). This folder can be deleted easily by right click on it and choose delete, or directly you can press the shift + Del button to delete it. But here we are going to talk about a Folder which you cant delete or modify. Confusing right, Ok let’s jump into the topic. Before proceeding into this topic, first, you have to know what is reserved keyword in windows. Reserved Keywords are used in operating systems as a method of identifying a device file or another service. In Windows or MS-DOS operating system there are Specific Reserved Keywords that are already used by some other file operation or service. If you try to create a file or folder using that particular Reserved keywords, windows will through an error like access denied error or say the file already exists. Find the list of Reserved keywords in windows or MS-DOS. CON, PRN, AUX, CLOCK$, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9 In this post I am going to show how to make the folder undeletable by using reserved keywords.
Follow the steps below to create a undeletable folder:
Open cmd in admin mode, To open the command in admin mode press WIN + X and select the command prompt(Admin). Open any drive in command prompt To open any drive just enter the Drive letter Like E: , F: , D: and hit enter. Now type md con\ 
What is MD?
Md is making the directory in the command prompt.
What is CON?
This folder names as console file, copy con file takes the text typed into the console and puts it into FILE, Stopping When EOF (Ctrl + Z) is typed. Now what happened you created a folder names as con in the E: directory, check it whether it worked or not. Confirm once. once the folder is created try to delete the folder and check. If it shows an error then put all your data folders inside.
So here is the way to delete the undeletable folder using the command.
Again open the command prompt in admin mode and type the drive letter again. Now type rd con\ Rd con\ will remove the directory. Your file is deleted now. 
