You needn't clear comments in a Word document one by one. Instead, bring out the big guns to delete all of them at once:
1. Chose Tools > Keyboard Shortcuts.
2. Under Categories, select Tools.
3. Under Commands, select DeleteAllCommentsInDoc.
4. With the insertion point in the "Press new keyboard shortcut" field, press keys to create a keyboard shortcut. (I use Control-7)
5. Click the Assign button.
6. Click OK.
You can now press your keyboard shortcut to zap out the comments.
The steps above work in Word 2008; they likely work nearly as described in older versions of Word.
From Tonya Engst