That vertical line is probably marking tracked changes. You can get rid of
it in at least two different ways.
The easiest way to get rid of it is to accept all tracked changes in the
document. You can do this from the Reviewing toolbar by clicking on the down
arrow next to the blue checkmark icon. This also gets rid of all tracked
changes.
If you need to keep the tracked changes, but don't want a revision bar in
the margin, go to Tools - Options - Track Changes and select "(none)" for
Changed Lines.
I hope this helps.
Fred
