Excel includes the capability to convert cell references (such as B2 or C7) to names you have defined within a document; exactly how you do this has been covered in other issues of ExcelTips. There is no inherent command that will convert from named references back to cell references.
Unfortunately, if you try to delete names already defined in a workbook, Excel simply replaces the results of formulas referencing the name with the #NAME? error. The only way to switch back to cell references is to edit each of the formulas that reference a name and replace the reference with a cell reference.