If you’ve previously setup private nameservers and wish to remove them, here’s how you do this.
Changing Custom Nameservers
Step 1: Login to your Client Area
Step 2: Click on Domains, then click on My Domains
Step 3: Click the “Wrench” icon next to the domain you wish to create nameservers for
Step 4: Click “Private Nameservers”
Step 5: Input the name of the server you wish to remove, click “Save Changes”
The nameserver will now no longer exist. Don’t forget to change the nameservers for any Domains that were using that nameserver back to one that works and understand that changing your DNS may cause downtime and could take up to 24 – 72 hours for DNS propagation across the internet.