How to: Programmatically Add and Delete Worksheet Comments
You can programmatically add and delete comments in Microsoft Office Excel worksheets. Comments can be added only to single cells, not to multi-cell ranges.
Applies to: The information in this topic applies to document-level projects and application-level projects for Excel 2013 and Excel 2010. For more information, see Features Available by Office Application and Project Type.
The following examples assume that there is a single-cell NamedRange control named dateComment on a worksheet named Sheet1.
To add a new comment to a named range
To delete a comment from a named range
The following examples assume that there is a single-cell Microsoft.Office.Interop.Excel.Range named dateComment on the active worksheet.