Does anyone know how to remove the ground glass on an RB series B 2x3?

I've removed the screws, but the glass won't budge.

At the front of the view hood at the ground glass is a clip. Push that clip forward to release the base of the view hood. Remove 1 lower screw from the view hood to view door retainers and loosen the other 1/2 to 1 turn. Slide the view hood bar from behind the other retainer then remove the view hood from the camera.
Remove the 4 screws from the rear ground glass retainer spring then slip the ground glass from the front spring and out of the camera.
Ground side faces the mirror on installation.

This unit doesn't have a spring retainer.

It's more of a frame unit with 4 screws that
must adjust the ground glass for focus.

Is there any information on how to adjust
the ground glass?

I have one from the late 1940's, it has the retainer spring for the view hood at the front center.

The ground glass springs/retainers have 2 screws front and rear.
Tripod mount the camera and focus on a target that is parallel to the film plane. Adjust for best overall focus with a loupe. I usually just check the center third of the ground glass once I set the retainers to the same position they were in before removal.