It wont be that easy, it will be a combination of both automated and manual work.
But you can first have a backup of universe and try deleting objects which looks obsolete or unnecessary. Run few reports (DeskI, WebI) and if they dont complain delete further.
There is a utility in BOB downloads List objects in a report for full client reports which can be used to list objects used in a set of reports.
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haider 
(BOB member since 2005-07-18)