When you buy your Nebula subscription, you'll be assigned a Nebula Account Owner (NAO). If you're not sure who your NAO is, you can contact the Support team for help. You'll find more information on how to do this in the Contact ThreatDown Support section.
It's important to note that you can't remove the NAO from your account without assigning a new one first. If you want to change your NAO, you'll need to contact Sales by clicking on your display name > Contact Us.