What is a good Latin translation for "No Rulers" as an isolated motto? Only thing I can find is Nec Principes.
I think the appropriate word for 'rulers' here is domini. Assuming your mood to be imperative, you could simply say Domini absint : 'let there be no rulers here'.
Or you might address those whom you wish to ban by following Virgil's procul, o procul este profani (loosely, 'begone, begone, you who don't belong here') with o procul este domini, 'be off with you rulers'.