The Table of Contents is required inside Atticus for the formatting to work properly, so you cannot delete it entirely. However, you can hide it so that it doesn’t show up in your exports. If you click the three dots beside the title in the left navigation panel, you’ll be able to select Include In > and then choose your preference.
Even if you click 'none,' will still export to an ePub, but only as a navigational tool in eReading devices, not as a separate page.