Help needed with text project!

Hi all. New to Shapr 3D and am preparing some lettering. I have created the bodies of the letters and extruded the edges to make 3D lettering successfully. Now, i’d like to cut out the inner letters and print those separately to make the tops of the letters so they have the inner printed in white, and the outer shape in black.

How do I do that? How can I delete the walls and just leave the face of the innards of the lettering?

Any help is MUCH appreciated!


Thank you!