This cannot be turned off in the most recent versions of Word. Your options
are to go ahead and process the changes (accept or reject) so that there are
no more tracked changes in the document, or -- better still -- to send the
document out as a PDF so that you can control how others see it. If you need
to retain a version containing tracked changes, you can save the document
under a new name before processing the changes.
When you send out a document containing tracked changes, you cannot control
how recipients view it. If the tracked changes are embarrassing, they're not
any less embarrassing just because you think you've hidden them. Anyone
receiving/viewing you document is perfectly free to set the view to
something other than final. In the most recent versions of Word, this
happens automatically -- and, by and large, it prevents a lot of problems.
Before Word 2003 (I believe that's when the change took effect), a document
retained the Final setting when you sent it out. Unfortunately, this was the
source of many problems for many users--documents acted "funny" because
people weren't aware that they contained tracked changes. Now, at least,
recipients know that the document contains tracked changes.