How do I reset the Jupyter/IPython input prompt numbering?

Question

I just wrote my first extensive Python tutorial using IPython notebooks. All went well, except I did a lot of testing and moving blocks around. How do I reset the In [

Answer 1

Restart & Run All isn't a good solution, because simply I don't want to run all (and that's the purpose of a notebook to run things cell by cell).

Anyways, I found this solution more plausible:

Main Menu > Cell  > All Output > Clear