Locate the one, scroll wheel, #0 Phillips screw near the very front edge of the mouse.

Turn the mouse 90 degrees clockwise.

While supporting the rear of the mouse base, unscrew the #0 Phillips scroll wheel screw.

Set the screw to the side for reassembly.

Once the scroll wheel screw is fully removed, manually extract the scroll wheel and spring assembly.

Set the remains of the base of the mouse to the side.