Remove model default

[sibylle_k]

I have set a diagram as model default. Now I want to go back to the previous state not to open a diagram when I open the project. How do I "unset the model default"?
Note: I don't want to delete the diagram. I just want to stop it popping up at the beginning.

[thomaskilian]

Try to create a dummy diagram, set this as model default and finally delete that. There might be a better solution, though