How to disable legacy editor

I'm developing a site with slice machine, but for some reason the legacy editor is turned on.

The option to enable/disable it also does not appear in the settings section.

How can I get the option to appear to turn it off as I'd rather not have it as an option.

Thanks URL is *********

Hi Tim,

I think there's been a bit of misinformation here. For the moment turning off the legacy builder is only available for newly created repositories. We will make this more widely available in the future, though.

If your concerns are around editing access, then you can’t edit Slice Machine Slices in the legacy builder anyway. Also, user roles will stop certain users from accessing the legacy builder.