Somehow, I managed to set a passwd for my _postgres user on my OS instead of setting it on the postgres role I have as my superuser / root. Anyways since this, I've been struggling with that user showing up in the account section and login screen, which I really would like to avoid. I've read through some docs about this, and setting the password to * should be all that is needed to fix this. But after several attempts doing this with and without dscl to no avail, I'm gotten to a point where I don't know what to do anymore.

I didn't think it would be even hard doing this, but clearly I'm missing something, so how do you do this?