Any idea how you remove structural models from the piping input after you've imported one and then decided you want it removed (or modified)? I can't find anywhere to delete them.

I thought you just needed to clear out the reference to it in the auxiliary screen.

Yes, Ed is right. Just go to the "Structural Include" dialog and delete the reference to the particular structural file. This will remove it from the overall model. Be sure to check the restraints where the structural model as previously attached to ensure you don't have any free CNODEs left!

(Removing the structural file can be done by simply deleting its reference because the models are not combined until you go through error checking.)