Can't recall off of the top of my head exactly how it comes off but
this should help.

There should be a couple of screws where you grab the panel to close
the door. They may or may not have plastic pop off covers over them.
Also there is a screw behind the inner door handle. Can't recall if
that piece is part of the handle or if it is a separate piece. If it is
a separate piece remove it. If it is part of the handle remove the
screw and slide it forward, there are 2 plastic tabs that lock into the
door. Be careful, they break easily. Once you have the panel loose you
will have to work the handle thru the cut out in the panel.

If it has a removable speaker cover, there are screws behind there. I
think there are 2 screws on the inner/upper part of the cover and then
it hinges off. In other words remove the 2 screws and lift that part of
the cover up, the other part is secured with plastic tabs that slide
into the door panel. Can't remember if the speaker has to come out, or
if it is attached to the dr itself. You will be able to tell once you
have the cover off.

Or your cover my be part of the dr panel and can't be removed.

Look for any other visible screws or plastic pop off covers that have
screws under them. Then just starting pulling the panel off starting at
the bottom back corner.

Once you have the sides and bottom loose you will probably have to
unplug the small light at the bottom. (if you have one) Once that is
loose simply lift the door panel up and off. Don't forget about working
the door handle thru the cut out in the panel if it is a one piece unit
like I described above.

If you run into any snags while trying to lift the panel up make sure
there isn't a screw in the area that is snagged.

There are VERY easy to remove, once you get started you will see that
it's no big deal.

I'm assuming you have power windows? If so you would be correct about
it being the regulator. For some reason they only last about 5-6yrs (if
you are lucky) before they fail.

Hope this helps. I work on so many different types of cars I can
usually only remember exactly how the panels come off when they are in
front of me.