How to delete all comments in the spreadsheet
There are several different ways how to delete all comments in your spreadsheet quickly, but the fastest and easiest is to:
1. Select all cells in your spreadsheet. For example, by clicking Ctrl+A (see also Quick way to select all cells for more details).
2. On the Review tab, in the Comments group, click the Delete button:
See also this tip in French: Comment supprimer tous les commentaires dans la feuille de calcul.