How do I get rid of Real old Balance Sheet accounts?

I own a business that use to be a segment of a combined business.  The  I have owned QB PRO since early 2000's and accounts were transfered manually by the old bookeeper from Businessworks. As the main business segment died and we stopped renting office space and now own a successful in home bizz. Many assets that are long gone on the balance sheet became place holders with no info on how the offset accounts were made   That info is gone and some still shows  on the books.  The QB pro has been updated 3 times, my bookeeper is a pro advisor as was the earlier one.  The CPA has moved and does stuff remotely but knows little about quickbooks  My business is a communications Tower c.o. and is unique with leases These professionals have shied away from dealing with this. I need to get the books clean. I have old machinery& equipment accounts, leasehold improvements, accumulated depreciation, Furniture that was donated when we left the leased property, and basically I believe some accounts were used as catch alls , but pre 2003!  Should I rebuild the books or work on figuring corrections?  I am looking to find out options on where to go. Is there a way to trash the accounts that were part of the old business @ contra accounts?  Any direction would be appreciated