If you do that you really increase expense for the current year, and from what you say it was in a past year.

You need a tax accountant for this.

Depreciation expense - the IRS does not care if you take it or not during the period you should.  But, the kicker is the IRS requires that you calculate the gain/loss on the asset sale as if depreciation was entered.  How you make entries to use an expense/contra asset entry, that does not apply to current operations, when selling the asset, is beyond me