How to close cmd or command window?

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I use a network computer at work with Windows XP professional. The
signature files for Outlook are unacceptable. I tried changing them, but
no luck - they are changed back each time Outlook is started. I also
tried changing the .ini file, but it too is changed back.

I devised a work around using a .bat file to remove the read only
attribute from the signature files and overwriting them with acceptable
signature files. The only problem now is the cmd or command (tried both)
window won't close itself. I've tried various combinations with start,
cmd and command, but no luck. How can I get the command window to close
automatically?