How to restore the built-in "Create Task" form?

I’ve tried to experiment with the task creation forms in our Phabricator installation, but instead of creating a new form, I clicked on “make editable” on the built-in form (it was the only one existing).

Is there a way that I can restore the “built-in” property of that form and make it un-editable again, so that I do not accidentally change it?