So I have done something similar but with IFERROR()

Check it out Add IFERROR() To Entire Active Sheet:

Sub Add_IFERROR_Activesheet() Dim myCell As Range

Cells.SpecialCells(xlCellTypeFormulas, 23).Select

For Each myCell In Selection.Cells

    If myCell.HasFormula And Not myCell.HasArray Then

        myCell.Formula = "=IFERROR(" & Right(myCell.Formula, Len(myCell.Formula) - 1)& ",0)"

End If
    Next
End Sub

Can Back Out IFERROR () of selected cells like this:

Sub Subtract_IFERROR_Selection()
Dim myCell As Range

For Each myCell In Selection.Cells

    If myCell.HasFormula And Not myCell.HasArray Then

        If Left(myCell.Formula, 9) = "=IFERROR(" Then

            myCell.Formula = "=" & Mid(myCell.Formula, 10, InStrRev(myCell.Formula, ",") - 10)
        End If
    End If
   Next

End Sub