How to delete a shortcut with command line ?

You delete a shortcut just as you would delete any other file.  A shortcut will end with the extension ".lnk".  So assuming that you are trying to delete the shortcut named "Shortcut.lnk" that appears on the user "Bob"s desktop, you would use the delete (del)  or "erase" command specifying the entire path to the file.  (Be sure to put filename in quotation marks if there is a space anywhere in the path or name) as in:

    del  "C:\documents and settings\Bob\Desktop\Shortcut.lnk"

What kind of a "local users and groups" backup do you want to make?  If it is a backup of the users and groups as entered in the registry, a good registry backup program such as ERUNT will do this from the command line.  If you're trying to back up all users and their data as well, then you are better off with a backup program.

HTH,
  JW