I have seen two files "ntuser.dat" for many times. I want to delete them!?

The NTUSER dat file is actually one of your Registry files.

Unlike the other Registry files, NTUSER.DAT is stored in your personal Documents and Settings folder and contains the entire contents of the HKEY_LOCAL_USER branch of the Registry.

You can’t delete it because it’s in use and protected, and you wouldn’t want to because otherwise you’ll mess up your whole computer!

It will grow as you install more software that creates keys and sub keys in this branch of the Registry, and so is perfectly normal.

To summarise: leave NTUSER.DAT alone.

I've learned, if you don't know what a file is then don't delete it. ntuser.dat is a registry file and there isn't a safe way to delete it...unless you want to change your operating system, sounds like you have windows, expensive and they have files on there that you can't open, they save everything that you have done so you can be watched in case you are a terrorist or something. Uninstall windows and download Linux and use that instead, it is free and won't have any files that you cannot open. If you have anymore questions just Google ntuser.dat or linux.

Do not touch,it seems they are registry files,your pc needs them.

They're user data files -Only delete them when the associated file is no longer in use