1965 valiant front fender removal

Not sure if you HAVE to remove bumper, I would think it probably does but you can remove the bumper with the mounting brackets rather easily by removing four bolts where it is attached to frame rails.
There are no welds so the fender will come off but it will have the head light bucket welded to it.
I think your '65 has a '66 front clip ( fenders, hood & grill ) if I remember correctly.