If you want to hide or show comment indicator red triangles from Excel worksheet Cells, you can do it from Excel Options dialog box window, as explained below.
Open Excel Options dialog box window from Excel Backstage View. Open "Advanced" Panel by clicking on it in left-side menu. Scroll down to "Display" heading. You can see that there are three options related with display of Comments in Excel worksheet, as shown in below image.
• "No comments or indicators" - If you select "No comments or indicators" radio button, no comments or red triangle indicators will be shown on Cells which has comments until you click Excel Ribbon > Review Tab, Comments Group and click "Show all Comments" button or Excel Ribbon > Review Tab, Comments Group and click "Show/Hide Comment" button. If you select this option, Comment indicator red triangles will be hidden.
• "Indictors only, and comments on hover" - This is the default option. If you select this options, red triangle indicators will be shown on Cells which has Comments and Comments will be displayed once mouse pointer is kept over the Cell, which has a Comment.
• "Comments and indicators" - Both Comments and indicators will be displayed.