Deleting

If you delete a named range which is being used in a formula the formula will return #NAME?.
You cannot undo the deletion od a named range using (Edit > Undo).
If you delete rows and columns that contain named cells or ranges then the named ranges will become invalid.
The cell references used by the named ranges will then contain #REF!.
In this case the named ranges are not automatically deleted.

If you have a workbook level named range that refers to Sheet1 and you delete Sheet1, the named range remains but contains #REF!.