When you type net file, it lists the files on your computer that are opened remotely.

NOTE: See tip 3486 ยป How do I close all opened shared files on my 'server'?.

PsFile freeware will do the same thing, plus it can work remotely, and it can close open files by name or by file identifier.

When you type PsFile /?, you receive:

                              PsFile v1.01 - local and remote network file lister                              Copyright (C) 2001 Mark Russinovich                              Sysinternals - www.sysinternals.com                              PsFile lists or closes files opened remotely.                              Usage: psfile \[\\RemoteComputer \[-u Username \[-p Password\]\]\]  path\] \[-c                                   -u        Specifies optional user name for login to                                             remote computer.                                   -p        Specifies password for user name.                                   Id        Id of file to print information for or close.                                   Path      Full or partial path of files to match.                                   -c        Closes file identified by file Id.                              Omitting a file identifier has PsFile list all files opened remotely.