The only way to achieve your desired result is to simply save a version of the finished document with the comments removed. Even better is that the document can be saved very quickly and easily as a new file by pressing F12
to bring up the 'Save As...' dialog box.
I hope this helps.
UPDATE:
To remove all comments at once:
Word 2007:
- Select the
Review
tab from the ribbon;
- From the
Comments
group, click the small arrow to the right of the Delete
button;
- Next, select
Delete All Comments in Document
With regards to file space, it would not take up twice as much space as you will have removed portions of the revised document, hence technically making it smaller; consider it to be marginally smaller than the original version with comments. However, it will certainly take up more space on your hard drive (or cloud drive) as you will be saving two documents. With respect, today's storage mediums are more than capable of storing truly phenomenal amounts of data, so I wouldn't imagine that it would cause any problems. Even the most basic memory sticks and the like store around 1GB of data, which is plenty to accommodate two MS Word documents.
I hope that this has made your task a little easier.