I cant figgure out how to un register outlook and register to a new user

[Dan Leech]

we have a new hire thats sitting at an old desk .....I
uninstalled office and reinstalled it ..and now its
saying its already been activated by the old user and
that we only have 30 days left ...but the old user is no
longer using it or anything ...so what do I do to get rid
of this message?

Thanks!

Dan Leech