moving from wordpress.com to private host – nameserver update

I’m ready to move the domain name from wordpress.com to my private host but can’t see the name server options as per this instruction https://en.support.wordpress.com/domain-mapping/domain-management/

I can see edit DNS, but on that screen I can only update the DNS records and not the name servers. Your help would be appreciated. I need to have the new website live on July 1!

thanks

Vanessa