C # Small problem about deleting sheet when calling EXCEL

When you use C # To adjust the worksheet. Delete of an Excel object to delete the sheet in a file, it is always impossible. Later I found the problem:

By default, when the appliation. Open file is set to false, the system only operates in the background without a macro. In this case, if you only call Delete to delete a file, a dialog box for confirming the deletion is displayed. However, the deletion is not completed because the dialog box cannot be seen in the background operation. The problem is detected only when visible is set.

Workbook. displayalerts = false.