How it works
Delete comments allows you to delete all comments from your current workbook with just two clicks.
How to use it:

Step 1
In the ‘More’ drop down of the Formatting and Grooming group, click on ‘Delete Comments’.
A new pop-up window will appear.

Step 2
Select if you want to delete all comments in the current workbook or all workbooks.
Yes = Everything & No = Current Only
On selection, the function will run.