Follow the instructions below to remove a DNS zone via the NS1 portal.
Navigate to DNS > Zones from the main navigation.
Locate and click the name of the zone you want to delete, and then select the Zone Settings tab.
Scroll to the bottom of the page and click Delete Zone in the bottom right corner.
This action cannot be undone. If you proceed, you must update the zone's TLD delegations from NS1 to your new provider. NS1 has controls in place to prevent lame delegation hijacking, but you should update TLD delegations to point to your new provider as soon as possible.
After reviewing the warning message, click Delete Zone to proceed.