In article .com,
wrote:

I don't think there's a need to scribe - this is my first project and
its going into a closet that only my wife and I will see. The walls
aren't THAT wavy, and most of all I'm not working to those kind of
tolerances that I can follow a scribed line that is not straight. My
skills aren't there yet. I just need to shave off a straight line and
that's good enough.

I don't have a belt sander, but I've got a 1/4 sheet finish sander -
would that have enough power to do it? Wouldn't it just pull the
plywood apart at the edge?

the 1/4 sheet finish sander is likely to bugger up the job and take
forever doing it.



Would either a sander or circular saw mess up the urethane finish just
next to the cut line?


circular saw or router would be my choice out of the tools you
mentioned. use a straight edge clamped on as a guide with either of
them. masking tape will protect the surface.